Divergent Synthesis of Highly Substituted Tetrahydroquinolines and Cyclopentenes via Lewis Base Catalyzed Switchable [4 + 2] and [3 + 2] Annulations of MBH-Carbonates with Activated Olefins.

A highly selective and divergent synthesis which enabled access to various complex compounds is highly attractive in organic synthesis and medicinal chemistry. Herein, we developed an effective method for divergent synthesis of highly substituted tetrahydroquinolines via Lewis base catalyzed switchable annulations of Morita-Baylis-Hillman carbonates with activated olefins. The reaction displayed switchable [4 + 2] or [3 + 2] annulations via catalyst or substrate control, providing a diverse range of architectures which contained highly substituted tetrahydroquinolines or cyclopentenes with three contiguous stereocenters bearing a quaternary carbon center in high yields with excellent diastereoselectivities and regioselectivities. Furthermore, synthetic utility of this strategy was further highlighted by gram-scale experiments and simple transformations of the products.

Substrate-Controlled Regioselectivity Switchable [3 + 2] Annulations To Access Spirooxindole Skeletons.

The additive-free [3 + 2] annulation from isatins, amino acids with 2-styrylbenzoxazoles, was described, providing a series of functional and structurally complex 3,3'-pyrrolidinyl-spirooxindole derivatives containing four contiguous and two quaternary stereogenic centers in high yields (up to 95%) and excellent diastereoselectivities (up to >25:1 dr). Interestingly, the reaction exhibits switchable regioselectivity depending on the substrate of amino acids. With proline or thioproline as the substrate, the reaction afforded α-regioselective spirooxindole skeletons. In contrast, when piperidine acid is the substrate, the reaction provided γ-regioselective spirooxindole skeletons.

A copper iodide-catalyzed coupling reaction of benzofuran-3(2H)-ones with amines: an approach to α-ketoamides.

A CuI-catalyzed coupling reaction of benzofuran-3(2H)-ones with amines has been well established for the direct synthesis of α-ketoamides. This process involves C-O bond cleavage and C[double bond, length as m-dash]O/C-N bond formation. Mechanism studies indicated that this α-ketoamide formation reaction may involve a free radical process.

Synthesis of γ-Lactones by TBAI-Promoted Intermolecular Carboesterification of Carboxylic Acids with Alkenes and Alcohols.

A novel tetrabutylammonium iodide (TBAI)-promoted three-component reaction of carboxylic acid with alkene and alcohol has been developed, which represents facile and straightforward access to polysubstituted γ-lactone skeletons in moderate-to-good yields. This methodology is distinguished by the use of a commercial catalyst and readily available starting materials, wide substrate scope, and operational simplicity. Mechanistic studies suggested that this transformation went through a radical process.

Cross 1,3-dipolar cycloadditions of C,N-cyclic azomethine imines with an N-benzyl azomethine ylide: facile access to fused tricyclic 1,2,4-hexahydrotriazines.

A cross 1,3-dipolar cycloaddition of two different ylides between C,N-cyclic azomethine imines with an in situ-generated nonstabilized azomethine ylide from an N-benzyl precursor was realized. The reactions afforded a clean and facile access to diverse fused tricyclic 1,2,4-hexahydrotriazines in high yields (up to 96%). The chemical structures of the typical compounds were confirmed by X-ray single-crystal structure analysis.

N-Heterocyclic Carbene/Lewis Acid Dual Catalysis for the Divergent Construction of Enantiopure Bridged Lactones and Fused Indenes.

The chiral triazole carbene and Ti(OPr-i)4 cocatalyzed reaction between α,ß-unsaturated aldehydes and 2-(aroylvinyl)benzaldehydes was systematically studied. A divergence in reaction pathways was observed under different reaction conditions. In benzene solvent and at ambient temperature, the reaction produced 4,5-dihydro-1,4-methanobenzo[c]oxepin-3-ones, the bridged caprolactones, as the major products in moderate yields with excellent enantioselectivity. The same reaction in dichloroethane and at 50 °C, however, gave 2,8-dihydrocyclopenta[a]indenes as the major products in most cases. The application of the method developed was demonstrated by the transformation of the bridged lactone products into enantiopure 4-hydroxy-1,2,3,4-tetrahydronaphthalene-2-carboxylic acids.

The Reaction of 2-Aroylvinylcinnamaldehydes with Aromatic Aldehydes by Dual Catalysis with a Chiral N-Heterocyclic Carbene and a Lewis Acid: Enantioselective Construction of Tetrahydroindeno[1,2-c]furan-1-ones.

The cooperative chiral N-heterocyclic carbene and Lewis acid catalyzed reactions between 2-aroylvinylcinnamaldehydes and various aromatic aldehydes produced multifunctional tetrahydroindeno[1,2-c]furan-1-ones with excellent enantioselectivity. This work developed a versatile and efficient method for highly enantioselective construction of chiral tetrahydroindeno[1,2-c]furan-1-one, which are not easily prepared by other synthetic methods.

N-heterocyclic carbene-catalyzed diastereoselective and enantioselective reaction of 2-aroylvinylcinnamaldehydes with α,ß-unsaturated imines: complete control and switch of diastereoselectivity by N-substituents of catalysts.

Highly diastereoselective and enantioselective reactions between 2-aroylvinylcinnamaldehydes and α,ß-unsaturated imines were achieved under asymmetric catalysis of chiral triazole carbene catalysts. In the presence of N-anisylindeno[2,1-b]triazolo[4,3-d][1,4]oxazinium salt, the reaction of 2-aroylvinylcinnamaldehydes with α,ß-unsaturated imines afforded indeno[2,1-c]pyran-1-one derivatives 4 with 90%-99% ee, while enantiopure indenocyclopentan-1-ones 5 (>99% ee) were obtained under the catalysis of N-mesitylindeno[2,1-b]triazolo[4,3-d][1,4]oxazinium salt. A slight variation of an N-substituent on triazole carbenes was found to switch completely the diastereoselectivity of the reaction for the formation of indeno[2,1-c]pyran-1-ones.

N-Heterocyclic Carbene-Catalyzed Oxidative Annulations of α,ß-Unsaturated Aldehydes with Hydrazones: Selective Synthesis of Optically Active 4,5-Dihydropyridazin-3-ones and Pyridazin-3-ones.

A novel and efficient method for the highly enantioselective synthesis of chiral 4,5-dihydropyridazin-3-one derivatives has been developed based on the chiral N-heterocyclic carbene-catalyzed oxidative annulation between α,ß-unsaturated aldehydes and hydrazones. Meanwhile, the selective synthesis of either 4,5-dihydropyridazin-3-ones or pyridazin-3-one derivatives from the same reactants has been achieved by simply varying catalytic and reaction conditions.

[Energy-saving and Emission Reduction Path for Road Traffic in Key Coastal Cities of Guangdong, Fujian and Zhejiang].

The rapid development of society and economy has resulted in a substantial increase in energy consumption, consequently exacerbating pollution issues. Current research predominantly focuses on energy-saving and emission reduction in road transportation within individual cities or the three major economic regions of China:the Yangtze River Delta, the Pearl River Delta, and the Beijing-Tianjin-Hebei Region. However, there is a dearth of studies addressing the southeastern coastal economic region. Located at the heart of China's southeastern coastal economic development, the provinces of Guangdong, Fujian, and Zhejiang unavoidably face challenges associated with energy consumption and emissions while pursuing economic growth. To address these challenges, this study employed a LEAP model to construct various scenarios for road transportation in the key coastal cities of Guangdong, Fujian, and Zhejiang from 2015 to 2035. These scenarios included a baseline scenario (BAU), an existing policy scenario (EPS), and an improved policy scenario (MPS). The MPS and EPS encompassed vehicle structure optimization (VSO), improved fuel economy (IFE), and reduced annual average mileage (RDM). By simulating and evaluating these scenarios, the energy-saving and emission reduction potentials of road transportation in the key coastal cities were assessed. The results indicated that, in the primary scenario, the MPS exhibited the most significant improvements in energy-saving, carbon reduction, and pollutant reduction effects. By 2035, the MPS achieved a remarkable 75% energy-saving rate compared to that in the baseline scenario, accompanied by reductions of 68%, 59%, 66%, 70%, and 64% in CO2, CO, NOx, PM2.5, and SO2 emissions, respectively. In the secondary scenario, the improved scenario of enhancing fuel economy achieved a notable 30% reduction in energy consumption. Additionally, the scenarios involving vehicle structure adjustment (yielding reductions of 36%, 30%, 36%, 26%, and 40%) and annual average mileage reduction (resulting in reductions of 37%, 37%, 36%, 37%, and 36%) demonstrated significant reductions in CO2, CO, NOx, PM2.5, and SO2 emissions.

Palladium-catalyzed Suzuki-Miyaura coupling of aryl sulfamates with arylboronic acids.

Readily available NHC-Pd(II)-Mp complexes 2 showed efficient catalytic activity toward the Suzuki-Miyaura coupling of aryl sulfamates with arylboronic acids or potassium phenyltrifluoroborate, giving the expected coupling products in good to high yields. It should be noted that this is the first example so far of the phosphine-free, NHC-Pd(II) complexes catalyzed Suzuki-Miyaura coupling of aryl sulfamates with arylboronic acids.

Highly regioselective synthesis of lactams via cascade reaction of α,ß-unsaturated ketones, ketoamides, and DBU as a catalyst.

Herein, the aldol/Michael cascade reaction on the ß,γ-positions of α,ß-unsaturated ketones with ketoamides to construct bicyclic lactams via DBU catalysis has been developed. The substrates were well-tolerated with high regio- and diastereoselectivities in moderate to good yields (32 examples). The control experiments revealed that the hydrogen of the amide was the key factor.

N-heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed Suzuki-Miyaura coupling of aryl sulfonates with arylboronic acids.

A well-defined NHC-Pd(II)-Im complex 1 was found to be an effective catalyst for the Suzuki-Miyaura coupling of aryl sulfonates including tosylates and phenylsulfonates with arylboronic acids, giving the desired coupling products in good to high yields. Acceptable yields can also be achieved even by using the less reactive mesylates as the substrates. It is worthy of noting here that this is the first example of NHC-Pd(II) complex-catalyzed Suzuki-Miyaura coupling of aryl sulfonates with arylboronic acids, enriching an inexpensive, convenient, and alternative method for the synthesis of biaryl compounds.

[3 + 2] cycloaddition of nonstabilized azomethine ylides and 2-benzothiazolamines to access imidazolidine derivatives.

A simple and practical method for the construction of 1,3,5-trisubstituted imidazolidine derivatives via [3 + 2] cycloaddition reaction has been developed. This reaction could smoothly proceed between nonstabilized azomethine ylides generated in situ and 2-benzothiazolamines to deliver a wide scope of differently substituted imidazolidines in high yields (up to 98%). The structure of one example was confirmed by X-ray single-crystal structure analysis.

1,3-Dipolar cycloaddition of isatin N,N'-cyclic azomethine imines with α,ß-unsaturated aldehydes catalyzed by DBU in water.

A simple and green procedure was established by [3 + 3] cycloaddition reaction of isatin derived cyclic imine 1,3-dipoles with α,ß-unsaturated aldehydes, giving the desired spiro heterocyclic oxindoles with aza-quaternary centers in good yields and diastereoselectivities. It should be noted that water can be employed as a suitable solvent for the improvement of diastereoselectivity.

Dearomative [3 + 2] cycloaddition reaction of nitrobenzothiophenes with nonstabilized azomethine ylides.

A highly diastereoselective dearomative [3 + 2] 1,3-dipolar cycloaddition reaction of nitrobenzothiophenes with an in situ-generated nonstabilized azomethine ylides has been developed. The transformation provides a series of functionalized fused tricyclic benzo[4,5]thieno[2,3-c]pyrroles in good yields (up to 92%) under mild reaction conditions. In addition, a gram-scale experiment and the synthetic transformation of the cycloadduct further highlighted the synthetic utility. The relative configurations of the typical products were clearly confirmed by X-ray crystallography.

Molecular prenatal diagnosis of alpha-thalassemia using real-time and multiplex polymerase chain reaction methods.

Molecular analysis of two fetuses at high risk of alpha-thalassemia (alpha-thal), and their family members, was performed using real-time polymerase chain reaction (PCR) with SYBR Green 1 (SYBR-PCR) dye combined with dissociation curve analysis and multiplex PCR (m-PCR) and DNA sequencing techniques. The genotype of the fetus from one family was --SEA/--SEA (Southeast Asian deletion), which produces hydrops fetalis syndrome. The genotype of the parents was --SEA/alphaalpha. A boy with Hb H disease and his sibling fetus from the other family had the genotype --SEA/alphaCSalpha [the Hb Constant Spring (CS) mutation: alpha142, Term-->Gln (TAA>CAA in alpha2)] and alphaalpha/alphaalpha (normal), respectively. The diagnosis, based on SYBR-PCR combined with dissociation curve analysis, was in agreement with the results from the m-PCR method. This indicates that these are alternative and reliable assays for the molecular diagnosis of deletional alpha-thal.

[Prenatal diagnosis for fetus with hemophilia A].

OBJECTIVE: To study the prenatal genetic diagnostic methods for hemophilia A fetus. METHODS: From 2002 to 2006, 19 hemophilia A families were diagnosed either by long distance-polymerase chain reaction (LD-PCR) for factor VIII intron 22 inversion or by the DNA polymorphism genetic linkage analysis of factor VIII in the Beijing Chaoyang Hospital. RESULTS: (1) Totally 19 women, with 22 pregnancies received the prenatal diagnosis of fetal hemophilia A. The average week at diagnosis was 23 (17-34 ) weeks. All the direct fetal blood sampling (DFBS) were successful. There was no fetal-loss caused by the procedures. (2) Of the 19 hemophilia A families, 14 appeared to be factor VIII intron 22 inversion, in which 16 prenatal diagnoses were done, 10 fetuses were diagnosed as genetical hemophilia A patients, and 6 fetuses were normal. (3) Using combined polymorphism genetic linkage analysis 6 prenatal diagnoses were done, including one woman's two pregnancies, in which both her fetuses were diagnosed as genetical hemophilia A patients. (4) Factor VIII levels of 16 fetuses were measured, and 6 fetuses were unmeasured either because the pregnancy weeks were lower than 20 weeks or the parents refused. Factor VIII level ranged from 0 to 198%. There were 11 fetuses whose factor VIII levels were lower than 10%. Ten of them were diagnosed to be genetical hemophilia A patients, and in only one boy the factor VIII level was 2%, but the genetic diagnosis was normal and for one year's follow up he was doing normal. CONCLUSION: LD-PCR combined with polymorphism genetic linkage analysis enables a quick and correct detection of hemophilia A carrier. For a carrier pregnancy, prenatal diagnosis could be done for the male fetus. Factor VIII deficiency of the fetus could help make the diagnosis but the final diagnosis should be based on genetic evidence.

[Improvement of gene analysis method in hemophilia A and its application of prenatal diagnosis].

OBJECTIVE: To establish a simple and rapid system for carrier detection and prenatal diagnosis in hemophilia A (CHA) family. METHODS: Long distance-polymerase chain reaction (LD-PCR) was selected for detection factor VIII intron 22 inversion. Polymorphism of factor VIII intragenic restriction fragment length polymorphism (RFLP) of Xba I and Hin d III, short tandem repeat (STR) within intron 13 and 22, as well as extragenic DXS52 (ST 14) variable number of tandem repeat (VNTR) were assayed by PCR and linkage analysis. RESULTS: Seventy-one females were diagnosed as carriers within 52 HA families. Twenty-one families were diagnosed to be factor VIII intron 22 inversion and 28 families were diagnosed by linkage analysis, whereas 3 families could not been diagnosed. Seventeen of 18 fetuses at risk were male. Ten of 17 male fetuses were shown to be affected and were subsequently aborted. Seven male fetuses were diagnosed to be not affected. One female fetus was identified to be HA carrier. One-year follow-up study demonstrated that these babies were normal and living well. CONCLUSION: LD-PCR combined with multiple locus linkage analysis enables the direct and indirect detection of HA for carrier testing and prenatal diagnosis.

[Detection of alpha thalassemia using real-time PCR and dissociation curve analysis].

OBJECTIVE: To establish an automatic, high throughput, quick detection method of alpha thalassemia. METHODS: The genotypes of -alpha(4.2) and -alpha(3.7) were detected by two real-time fluorescence PCRs using SYBR-Green1 (SYBR-PCR) with the analysis of dissociation curve (DC) and melting temperature (Tm). The PCR products were recombined into T-vector and the correct cloning was selected as positive control. Sensitivities were gained from a serious dilution of the recombinant as SYBR-PCR template, from which detection deadlines for two kinds of alleles could be determined. Totally 110 samples were detected by this technique. RESULTS: The length of product of -alpha(4.2) and -alpha(3.7) were 1.65 kb and 1.9 kb respectively, and the Tm were (81.5+/-0.5) degrees C and (82.5+/-0.5) degrees C respectively. The detection deadline were 9 x 10(2 ) copies and 4.3 x 10(2) copies respectively. The sensitivity of the technique was much higher than that of regular PCR plus gel electrophoresis method, and the detection results of the technique were the same as that of multiplex PCR. CONCLUSION: The genotypes of -alpha(4.2), -alpha(3.7), non-deletion alpha alpha/and --(SEA) can be sensitively, exactly diagnosed by the real-time PCR with SYBR-Green1 combined with the dissociation curve analysis. The assay is automatic, low-cost, high throughput, and easy for quality control without fluorescence probe.