Regio- and Diastereoselective Synthesis of Polysubstituted Piperidines Enabled by Boronyl Radical-Catalyzed (4+2) Cycloaddition.

Piperidines are widely present in small molecule drugs and natural products. Despite many methods have been developed for their synthesis, new approaches to polysubstituted piperidines are highly desirable. This work presents a radical (4+2) cycloaddition reaction for synthesis of piperidines featuring dense substituents at 3,4,5-positions that are not readily accessible by known methods. Using commercially available diboron(4) compounds and 4-phenylpyridine as the catalyst precursors, the boronyl radical-catalyzed cycloaddition between 3-aroyl azetidines and various alkenes, including previously unreactive 1,2-di-, tri-, and tetrasubstituted alkenes, has delivered the polysubstituted piperidines in generally high yield and diastereoselectivity. The reaction also features high modularity, atom economy, broad substrate scope, metal-free conditions, simple catalysts and operation. The utilization of the products has been demonstrated by selective transformations. A plausible mechanism, with the ring-opening of azetidine as the rate-limiting step, has been proposed based on the experimental and computational results.

Selective [2σ + 2σ] Cycloaddition Enabled by Boronyl Radical Catalysis: Synthesis of Highly Substituted Bicyclo[3.1.1]heptanes.

In contrast to the traditional and widely-used cycloaddition reactions involving at least a π bond component, a [2σ + 2σ] radical cycloaddition between bicyclo[1.1.0]butanes (BCBs) and cyclopropyl ketones has been developed to provide a modular, concise, and atom-economical synthetic route to substituted bicyclo[3.1.1]heptane (BCH) derivatives that are 3D bioisosteres of benzenes and core skeleton of a number of terpene natural products. The reaction was catalyzed by a combination of simple tetraalkoxydiboron(4) compound B2pin2 and 3-pentyl isonicotinate. The broad substrate scope has been demonstrated by synthesizing a series of new highly functionalized BCHs with up to six substituents on the core with up to 99% isolated yield. Computational mechanistic investigations supported a pyridine-assisted boronyl radical catalytic cycle.

Catalysis with Diboron(4)/Pyridine: Application to the Broad-Scope [3 + 2] Cycloaddition of Cyclopropanes and Alkenes.

In contrast to the extensive but non-recyclable use of tetraalkoxydiboron(4) compounds as stoichiometric reagents in diverse reactions, this article reports an atom-economical reaction using a commercial diboron(4) as the catalyst. The key to success was designing a catalytic cycle for radical [3 + 2] cycloaddition involving a pyridine cocatalyst to generate from the diboron(4) catalyst and reversibly mediate the transfer of boronyl radicals. In comparison with known [3 + 2] cycloaddition with transition metal-based catalysts, the current reaction features not only metal-free conditions, inexpensive and stable catalysts, and simple operation but also remarkably broadened substrate scope. In particular, previously unusable cyclopropyl ketones without an activating group and/or alkenes with 1,2-disubstitution and 1,1,2-trisubstitution patterns were successfully used for the first time. Consequently, challenging cyclopentane compounds with various levels of substitution (65 examples, 57 new products, up to six substituents at all five ring atoms) were readily prepared in generally high to excellent yield and diastereoselectivity. The reaction was also successfully applied in concise formal synthesis of an anti-obesity drug and building natural product-like complex bridged or spirocyclic compounds. Mechanistic experiments and computational investigation support the proposed radical relay catalysis featuring a pyridine-assisted boronyl radical catalyst. Overall, this work demonstrates the first approach to use tetraalkoxydiboron(4) compounds as catalysts and may lead to the development of new, green, and efficient transition metal-like boron-catalyzed organic reactions.

Diboron(4)-Catalyzed Remote [3+2] Cycloaddition of Cyclopropanes via Dearomative/Rearomative Radical Transmission through Pyridine.

Ring structures such as pyridine, cyclopentane or their combinations are important motifs in bioactive molecules. In contrast to previous cycloaddition reactions that necessitated a directly bonded initiating functional group, this work demonstrated a novel through-(hetero)arene radical transmission concept for selective activation of a remote bond. An efficient, metal-free and atom-economical [3+2] cycloaddition between 4-pyridinyl cyclopropanes and alkenes or alkynes has been developed for modular synthesis of pyridine-substituted cyclopentanes, cyclopentenes and bicyclo[2.1.1]hexanes that are difficult to access using known methods. This complexity-building reaction was catalyzed by a very simple and inexpensive diboron(4) compound and took place via dearomative/rearomative processes. The substrate scope was broad and more than 100 new compounds were prepared in generally high yields. Mechanistic experiments and density function theory (DFT) investigation supported a radical relay catalytic cycle involving alkylidene dihydropyridine radical intermediates and boronyl radical transfer.

Balancing skeleton and functional groups in total syntheses of complex natural products: a case study of tigliane, daphnane and ingenane diterpenoids.

Total synthesis of natural products has greatly contributed to natural product research, organic synthesis and drug discovery and development. However, in most cases, the efficiency of total synthesis is far from sufficient for direct practical industrial application. Thus, designing a concise and efficient synthetic route with balanced efforts between building the complex skeleton and introducing functional groups is highly desirable. In this critical review, we first present an introduction of this issue and a philosophical framework that cover possible synthetic approaches. Next, we have chosen the biogenetically closely related, biologically important and synthetically extremely challenging natural products, tiglianes, daphnanes and ingenanes as the particular case for the discussion, since in the past 40 years many synthetic approaches have been reported. The successes and pitfalls included therefore serve as the basis to draw some conclusions that may inspire future development in this area.

Recent Advances in Continuous-Flow Enantioselective Catalysis.

The increased demand for more efficient, safe, and green production in fine chemical and pharmaceutical industry calls for the development of continuous-flow manufacturing, and for chiral chemicals in particular, enantioselective catalytic processes. In recent years, this emerging direction has received considerable attention and has seen rapid progress. In most cases, catalytic enantioselective flow processes using homogeneous, heterogeneous, or enzymatic catalysts have shown significant advantages over the conventional batch mode, such as shortened reaction times, lower catalysts loadings, and higher selectivities in addition to the normal merits of non-enantioselective flow operations. In this Minireview, the advancements, key strategies, methods, and technologies developed the last six years as well as remaining challenges are summarized.

Total Synthesis of Prostratin, a Bioactive Tigliane Diterpenoid: Access to Multi-Stereocenter Cyclohexanes from a Phenol.

Tiglianes such as prostratin and related diterpenoids are biologically significant natural molecules and long-standing targets for organic synthesis community. Due to the complex polycyclic scaffolds, high oxygenation level, and dense functional groups and stereocenters, their de novo chemical syntheses still face formidable challenges despite extensive efforts in the past 40 years. This account details the development of a modular and concise synthesis of prostratin, a potent anti-HIV and anticancer agent. The key approach in this synthesis involved a sequence of oxidative dearomatization and sequential stereoselective installation of peripheral groups to rapidly build the contiguously substituted cyclohexane C-ring. Inspired by Wender's work, an acid- and solvent-controlled stereodivergent formation of cyclopropane D-ring was developed. Mechanistic investigations by computational methods revealed that the competition between intra- and intermolecular hydrogen bonding led to different conformations, thus favoring different protonation processes. The designed and unexpected chemistry along this campaign reflected the uniqueness of the natural structures and should be amenable to future chemical syntheses of related complex polycyclic molecules.

An Internet-Based Self-Testing Model (Easy Test): Cross-Sectional Survey Targeting Men Who Have Sex With Men Who Never Tested for HIV in 14 Provinces of China.

BACKGROUND: With China's explosive internet growth, activities such as socializing and partner seeking among men who have sex with men (MSM) has also become Web based through popular services such as Blued. This creates a new mode of health promotion with the potential to instantly reach large numbers of MSM, including those who rarely access traditional offline testing facilities. OBJECTIVE: This study aimed to assess the feasibility of the Easy Test in increasing access and uptake of HIV testing and treatment services among MSM and to identify demographic and behavioral predictors of program uptake to inform future implementation. METHODS: A feasibility study of the Easy Test model was conducted from October 2017 to December 2017 in 14 Chinese provinces. Applicants who provided informed consent completed a self-administered questionnaire and submitted a US $5 deposit to have the free test kit delivered to their homes. Orders were then received, processed, and posted by volunteers from local community-based organizations. Once applicants submitted images of their test results, the deposit was refunded to the applicant. Those whose test results were deemed to be HIV-positive were then connected to a peer navigator to accompany the individual to follow-up medical services. A chi-squared trend test was used to assess the relationship between lifetime HIV testing volume and HIV prevalence. Logistic regression models were used to identify independent risk factors associated with two outcomes: (1) never having tested for HIV and (2) receiving an HIV-positive result. RESULTS: A total of 879 individuals submitted Web-based requests for test kits. Their median age was 28 (interquartile range 24-34 years); 69.3% (609/879) had at least a college education, and 51.5% (453/879) had a monthly income between US $450 to $750; 77.7% (683/879) of the applicants submitted images of their test results, among whom 14.3% (98/683) had an HIV-positive result. Among the 42.9% (293/683) who were first-time testers, the HIV prevalence was 18.8% (55/293). Nearly three-quarters (71/98, 72.4%) of those with a positive test result were connected with a peer navigator and enrolled in treatment. Among the first-time testers, having multiple sexual partners (2-3 sexual partners: adjusted odds ratio [aOR] 2.44, 95% CI 1.08-5.50; 4 or above sexual partners: aOR 3.55, 95% CI 1.18-10.68) and reporting inconsistent condom use in the previous 3 months (aOR 7.95, 95% CI 3.66-17.26) were both associated with an HIV-positive result. An inverse dose response relationship between lifetime HIV testing volume and HIV prevalence was also observed in this study (χ23=55.0; P<.001). CONCLUSIONS: The Easy Test model reached a larger portion of first-time testers, many who reported higher risk sexual behaviors. This highlights the potential for an internet-based self-test model to increase access to HIV treatment services for HIV-positive MSM in China.

Spatial Analysis of the Human Immunodeficiency Virus Epidemic among Men Who Have Sex with Men in China, 2006-2015.

BACKGROUND: Studies have shown a recent upsurge in human immunodeficiency virus (HIV) burden among men who have sex with men (MSM) in China, especially in urban areas. For intervention planning and resource allocation, spatial analyses of HIV/AIDS case-clusters were required to identify epidemic foci and trends among MSM in China. METHODS: Information regarding MSM recorded as HIV/AIDS cases during 2006-2015 were extracted from the National Case Reporting System. Demographic trends were determined through Cochran-Armitage trend tests. Distribution of case-clusters was examined using spatial autocorrelation. Spatial-temporal scan was used to detect disease clustering. Spatial correlations between cases and socioenvironmental factors were determined by spatial regression. RESULTS: Between 2006 and 2015, in China, 120 371 HIV/AIDS cases were identified among MSM. Newly identified HIV/AIDS cases among self-reported MSM increased from 487 cases in 2006 to >30 000 cases in 2015. Among those HIV/AIDS cases recorded during 2006-2015, 47.0% were 20-29 years old and 24.9% were aged 30-39 years. Based on clusters of HIV/AIDS cases identified through spatial analysis, the epidemic was concentrated among MSM in large cities. Spatial-temporal clusters contained municipalities, provincial capitals, and main cities such as Beijing, Shanghai, Chongqing, Chengdu, and Guangzhou. Spatial regression analysis showed that sociodemographic indicators such as population density, per capita gross domestic product, and number of county-level medical institutions had statistically significant positive correlations with HIV/AIDS among MSM. CONCLUSIONS: Assorted spatial analyses revealed an increasingly concentrated HIV epidemic among young MSM in Chinese cities, calling for targeted health education and intensive interventions at an early age.

Copper-catalyzed aerobic cascade cycloamination and acyloxylation: a direct approach to 4-acyloxy-1H-pyrazoles.

A novel direct transformation of hydrazones to acyloxylated pyrazoles by copper-catalyzed regioselective olefinic C(sp(2))-H bond cycloamination and acyloxylation was performed under mild conditions, which combines the formation of the pyrazole skeleton and installation of an acyloxyl group in a single step, using facile carboxylic acids as the acyloxylation reagents.

The HIV, syphilis, and HCV epidemics among female sex workers in china: results from a serial cross-sectional study between 2008 and 2012.

BACKGROUND: Studies on the transmission of human immunodeficiency virus (HIV) and sexually transmitted diseases in female sex workers (FSWs) have been limited primarily to inferences drawn by focusing on defined geographical areas. METHODS AND FINDINGS: This serial cross-sectional study was conducted in mainland China from 2008 through 2012. Data for 827 079 participants was analyzed. We classified venues such as karaoke bars and hotels as high tier and venues such as hair salons and barbershops, massage parlors, and other public outdoor venues as low tier based on the participants' socioeconomic status. FSWs who worked at the venues and those who were present on the days of the survey were recruited. The prevalence of HIV decreased from 0.6% in 2008 to 0.3% in 2012, the syphilis prevalence ranged from 2.4% to 3.2% between 2008 and 2012, and hepatitis C virus (HCV) prevalence decreased from 0.9% in 2008 to 0.8% in 2012. Further, we found that HIV, syphilis, and HCV prevalence proportions were high in FSWs from low tiers. CONCLUSIONS: HIV, syphilis, and HCV prevalence among FSWs in our study decreased during the study period. Comprehensive intervention strategies, particularly those that focus on low-tier and older FSWs, are needed in order to decrease the disease burden in this population.

HIV/AIDS epidemic among older adults in China during 2005-2012: results from trend and spatial analysis.

BACKGROUND: Recent studies have indicated an increasing burden of human immunodeficiency virus (HIV)/AIDS among older adults. METHODS: All identified people living with HIV/AIDS (PLWHA) recorded through the Chinese HIV/AIDS CRS during 2005-2012 were included in the study, except for the cases that lacked specific spatial information. Trend tests and spatial analyses were conducted. RESULTS: Information about 73,521 PLWHA (aged ≥50 years) was collected during 2005-2012. Three provinces-Guangxi, Henan, and Yunnan-accounted for 54.4% of the identified cases during the study period. Compared with 2005, the ratio between residents and migrants among the study population decreased to 40.1% in 2012. The ratio of HIV-infected patients to AIDS patients and the ratio of males to females increased gradually among older infected adults. Results of spatial analysis indicate a clustered distribution of HIV/AIDS among older adults throughout the country. Hot spots were observed in 4 provinces (Guangxi, Henan, Yunnan, and Sichuan) and 1 municipality (Chongqing). A trend from central provinces toward southern provinces was also identified. CONCLUSIONS: The number and proportion of HIV/AIDS among older adults have increased in recent years. The hot spots showed movement from central to southern China. A focused intervention strategy targeting the older PLWHA is urgently required in China.

Antiretroviral therapy to prevent HIV transmission in serodiscordant couples in China (2003-11): a national observational cohort study.

BACKGROUND: On the basis of the results of the randomised clinical trial HPTN 052 and observational studies, WHO has recommended that antiretroviral therapy be offered to all HIV-infected individuals with uninfected partners of the opposite sex (serodiscordant couples) to reduce the risk of transmission. Whether or not such a public health approach is feasible and the outcomes are sustainable at a large scale and in a developing country setting has not previously been assessed. METHODS: In this retrospective observational cohort study, we included treated and treatment-naive HIV-positive individuals with HIV-negative partners of the opposite sex who had been added to the national HIV epidemiology and treatment databases between Jan 1, 2003 and Dec 31, 2011. We analysed the annual rate of HIV infection in HIV-negative partners during follow-up, stratified by treatment status of the index partner. Cox proportional hazards analyses were done to examine factors related to HIV transmission. FINDINGS: Based on data from 38,862 serodiscordant couples, with 101,295·1 person-years of follow-up for the seronegative partners, rates of HIV infection were 2·6 per 100 person-years (95% CI 2·4-2·8) among the 14,805 couples in the treatment-naive cohort (median baseline CD4 count for HIV-positive partners 441 cells per µl [IQR 314-590]) and 1·3 per 100 person-years (1·2-1·3) among the 24,057 couples in the treated cohort (median baseline CD4 count for HIV-positive partners 168 cells per µl [62-269]). We calculated a 26% relative reduction in HIV transmission (adjusted hazard ratio 0·74, 95% CI 0·65-0·84) in the treated cohort. The reduction in transmission was seen across almost all demographic subgroups and was significant in the first year (0·64, 0·54-0·76), and among couples in which the HIV-positive partner had been infected by blood or plasma transfusion (0·76, 0·59-0·99) or heterosexual intercourse (0·69, 0·56-0·84), but not among couples in which the HIV-positive partner was infected by injecting drugs (0·98, 0·71-1·36). INTERPRETATION: Antiretroviral therapy for HIV-positive individuals in serodiscordant couples reduced HIV transmission across China, which suggests that the treatment-as-prevention approach is a feasible public health prevention strategy on a national scale in a developing country context. The durability and generalisability of such protection, however, needs to be further studied. FUNDING: Chinese Government's 12th Five-Year Plan, the National Natural Science Foundation of China, and the Canadian International Development Research Centre.

[Mobility of HIV/AIPS and affecting factors anlysis in 2013, China].

OBJECTIVE: To analyze the factors of people living with HIV/AIDS and mobility in 2013 who were reported before 2012 in China. METHODS: Data were collected through China HIV/AIDS case reporting information system in 2012 and 2013. A total of 300 349 HIV/AIDS cases reported before 2012 have been included in this study and have been visited in 2013.SPSS software was used to conduct multivariate logistic regression model. RESULTS: A total of 300 349 HIV/AIDS cases have been included in the study and 5.4% (16 088/300 349) objects have changed their residential locations in 2013. The movements mostly happened inside local province, which accounted for 69.1% (11 114/16 088).In Yunnan,Guangdong, and Guangxi province, the mobile percentage were 85.8% (2 377/2 771), 58.5% (1 534/2 621) and 78.1% (1 470/1 883) that movements happened inside local province. Multivariate logistic regression analysis showed that male (12 478 cases,OR = 1.97, 95%CI: 1.03-1.12), HIV infection (12 125 cases,OR = 1.99, 95%CI: 1.92-2.0), 15-49 age group (15 144 cases,OR = 2.16, 95%CI: 2.00-2.32) were more mobile. CONCLUSION: The movements mostly happened inside local province in 2013 in China and population movements tends to happen in young men infected with HIV.

Broad-Scope (3 + 2) Cycloaddition of Cyclopropanes and Alkynes Enabled by Boronyl Radical Catalysis.

Cyclopentene skeletons are ubiquitous in natural products and small molecule drugs. The (3 + 2) cycloaddition of cyclopropanes and alkynes represents an efficient and atom-economic strategy for synthesizing these structures. However, the types of substituents on cyclopropane and alkyne used in previous works show evident limitations, restricting the application of this type of reaction to some extent. Herein, we report a broad-scope (3 + 2) cycloaddition of cyclopropanes and alkynes catalyzed by boronyl radicals. In this method, various substrates, such as mono-, di-, tri-, and tetrasubstituted cyclopropanes, as well as mono- and disubstituted alkynes, were compatible with up to 98% isolated yield.

Estimation and projection of the HIV epidemic trend among the migrant population in China.

OBJECTIVE: The migrant population is a vulnerable group for HIV infection in China. Understanding potential epidemic trends among migrants is critical for developing HIV preventative measures in this population. METHODS: The Estimation and Projection Package (EPP) model was used to process prefecture and county-level surveillance data to generate HIV prevalence and epidemic trends for migrant populations in China. RESULTS: The prevalence of HIV among migrants in 2009 was estimated at 0.075% (95% CI: 0.042%, 0.108%) in China. The HIV epidemic among migrants is likely to increase over the next 5 years, with the prevalence expected to reach 0.110% (95% CI: 0.070%, 0.150%) by 2015. CONCLUSION: Although the 2009 estimates for the HIV/AIDS epidemic in China indicate a slower rate of increase compared with the national HIV/AIDS epidemic, it is estimated to persistently increase among migrants over the next 5 years. Migrants will have a strong impact on the overall future of the HIV epidemic trend in China and evidence-based prevention and monitoring efforts should be expanded for this vulnerable population.

A unified approach for divergent synthesis of contiguous stereodiads employing a small boronyl group.

Acyclic contiguous stereocenters are frequently seen in biologically active natural and synthetic molecules. Although various synthetic methods have been reported, predictable and unified approaches to all possible stereoisomers are rare, particularly for those containing non-reactive hydrocarbon substituents. Herein, a ß-boronyl group is employed as a readily accessible handle for predictable α-functionalization of enolates with either syn or anti selectivity depending on reaction conditions. Contiguous tertiary-tertiary and tertiary-quaternary stereocenters are thus accessed in generally good yields and diastereoselectivity. Based on experimental and computational studies, mechanism for syn selective alkylation is proposed, and Bpin (pinacolatoboronyl) behaves as a smaller group than most carbon-centered groups. The synthetic utility of this methodology is demonstrated by preparation of several key intermediates for bioactive molecules.

[Data analysis of national HIV comprehensive surveillance sites among female sex workers from 2004 to 2008].

OBJECTIVE: To monitor the time trend of behaviors change related to HIV/AIDS epidemic and HIV prevalence, and to provide information and basis for comprehensive HIV prevention responses and evaluation of intervention effectiveness among female sex workers in China. METHODS: During the year of 2004 to 2008, a series of cross-sectional surveys were conducted among female sex workers in community recruited in both entertainment places and in street, during the defined timeframe, a face-to-face interview was conducted with uniformed questionnaire; while, the venous blood specimen was collected. The sample size was 400 per site per survey. RESULTS: In 15 continuous national HIV comprehensive surveillance sites among female sex workers from 2004 to 2008, the median of HIV prevalence was 0.0%; Prevalence (median) of syphilis respectively: 0.5%, 1.8%, 1.6%, 1.8% and 1.0%. The median of target subjects who used condom in the last commercial sex was: 81.8%, 80.5%, 84.6%, 87.0% and 88.9% respectively; the median of always used condom in commercial sex during the last month: 65.8%, 59.6%, 60.3%, 59.8% and 73.7%. The median of awareness rate on HIV/AIDS transmission of female sex workers was: 74.3%, 84.1%, 65.2%, 66.0% and 74.3%. The median of target subjects who attended HIV VCT services were: 12.4%, 20.4%, 25.8%, 25.3% and 31.7%. The median of the proportion of female sex workers who reached intervention in last year respectively: 46.4%, 76.1%, 72.1%, 95.0% and 90.8%. CONCLUSION: Condom use and HIV awareness rate need to enhance further among female sex workers. The proportion of female sex workers who attended VCT and knew their HIV testing result and the proportion of female sex workers who reached intervention in last year both increase. HIV prevalence rate among female sex workers is generally low, but high risk behaviors are still alarming. It is necessary to take more comprehensive and effective prevention measures and intervention.

[Retrospective research on proportion of HIV related death causes in nine counties in China].

OBJECTIVE: To investigate the proportion of HIV related death cause, and its years of potential life lost (YPLL) and work years of potential life lose (WYPLL) in project counties. METHOD: According to the protocol of the third national death causes surveillance and HIV related death causes surveillance, retrospective study was implemented including baseline investigation of deaths' name list, demography information, door-to-door interview and death causes deduction in Gejiu, Ruili and Longchuan county in Yunnan province, Yangdong county in Guangdong province, Luzhai county in Guangxi zhuang Autonomous Region, Weishi and Zhecheng county in Henan province, Xishui county in Hubei province and Gu'an county in Hebei province. RESULTS: The study was conducted among nine counties located in seven provinces. A total of 118 719 cases were included, raw mortality was 5.83 per thousand, 2002 death cases were related to HIV, which contributed 1.67% of total deaths. The average age of HIV death was 38.03 yearsow, which was earlier than the non-HIV-related life-span (63.10 years). The YPLL and WYPLL of HIV death was 33.80 years and 20.50 years, respectively, which had contributed the second highest average YPLL. CONCLUSION: HIV has an important proportion among all death causes, and has contributed severe average YPLL and WYPLL.

Estimating HIV incidence among key affected populations in China from serial cross-sectional surveys in 2010-2014.

INTRODUCTION: HIV incidence is an important measure for monitoring the development of the epidemic, but it is difficult to ascertain. We combined serial HIV prevalence and mortality data to estimate HIV incidence among key affected populations (KAPs) in China. METHODS: Serial cross-sectional surveys were conducted among KAPs from 2010 to 2014. Trends in HIV prevalence were assessed by the Cochran-Armitage test, adjusted by risk group. HIV incidence was estimated from a mathematical model that describes the relationship between changes in HIV incidence with HIV prevalence and mortality. RESULTS: The crude HIV prevalence for the survey samples remained stable at 1.1 to 1.2% from 2010 to 2014. Among drug users (DUs), HIV prevalence declined from 4.48 to 3.29% (p<0.0001), and among men who have sex with men (MSM), HIV prevalence increased from 5.73 to 7.75% (p<0.0001). Changes in HIV prevalence among female sex workers (FSWs) and male patients of sexually transmitted disease clinics were more modest but remained statistically significant (all p<0.0001). The MSM population had the highest incidence estimates at 0.74% in 2011, 0.59% in 2012, 0.57% in 2013 and 0.53% in 2014. Estimates of the annual incidence for DUs and FSWs were very low and may not be reliable. CONCLUSIONS: Serial cross-sectional prevalence data from representative samples may be another approach to construct approximate estimates of national HIV incidence among key populations. We observed that the MSM population had the highest incidence for HIV among high-risk groups in China, and we suggest that interventions targeting MSM are urgently needed to curb the growing HIV epidemic.