RESUMEN
SmI2-mediated reductive cyclization of ß-arylthio ketones to generate thiochroman derivatives is not a generally observed process and the reported examples are limited to geminal disubstitution in the substrates. The results of the current study show that the cyclization also occurs when other substitution patterns are present, affording a general approach to dihydrothiochroman-ols in good yields and high degrees of diastereoselectivity. Besides, the halogen substitution on ß-aryl is tolerated in most cases here although reductive dehalogenation has been reported to predominate in the reductive cyclization process. Dihydrothiochroman-4-ols were readily oxidized to thiochroman-4-ols in almost quantitative yields.
RESUMEN
BACKGROUND: China has the largest number of the elderly in the world. As the proportion of elderly is rapidly increasing among national reported HIV/AIDS cases, it is a concern about HIV epidemic among older MSM in China. However, studies on HIV prevalence and unprotected anal intercourse (UAI) among Chinese older MSM were relatively few or generally had small sample sizes. METHODS: English and Chinese articles published in peer-reviewed journals were identified by systematically searching 5 electronic databases including PubMed and through cross-referencing. Summary prevalence rates of HIV infection and UAI with male sexual partners were calculated, and analyses were performed using the software Comprehensive Meta-Analysis V2.0 and SPSS V17.0. Subgroup analyses were performed separately by sample size, study year, study location, recruitment settings and sampling method. RESULTS: Twenty eligible cross-sectional studies (3 in English and 17 in Chinese), published between 2005 and 2013, with a total of 2812 older MSM participants, were identified. Our meta-analyses showed that the prevalence of HIV, syphilis and UAI in the last 6 months were 11.6% (95% confidence interval [CI]: 8.0%-16.6%), 23.0% (95% CI: 15.8%-32.3%) and 79.5% (95% CI: 72.7%-84.9%), respectively. HIV prevalence increased over the study period (6.3% in 2003-2007; 8.6% in 2008-2009, and 11.5% in 2010-2011, trend test Chi-square = 7.02, p = 0.008). The pooled prevalence of HIV (11.6% vs. 5.2%, Chi-square value = 36.2, p < 0.001) and UAI (79.5% vs. 52.6%, Chi-square value = 440.04, p < 0.001) among older MSM were both significantly higher than among younger age group (age < 50 years). CONCLUSIONS: Older Chinese MSM have high prevalence of HIV and syphilis. Unprotected anal sex is common and further puts them at high risks of acquiring and transmitting HIV, which was one of reasons for the rapid increasing of national reported older male HIV/AIDS cases. Prevention intervention programs should be specially tailored for this high risk MSM subgroup.