Chemoselective, Regioselective, and <i>E</i>/<i>Z</i>-Diastereoselective Synthesis of 2-Alkylidenetetrahydrofurans by Sequential Reactions of Ambident Dianions and Monoanions
作者:Peter Langer、Esen Bellur
DOI:10.1021/jo034966f
日期:2003.12.1
A number of novel beta-ketoesters were prepared by regioselective alkylation reactions of simple beta-ketoester dianions. The cyclization of the dianions of these 1,3-dicarbonyl derivatives with 1-bromo-2-chloroethane afforded a variety of 2-alkylidenetetrahydrofurans with very good regioselectivity and E/Z-diastereoselectivity. These products were deprotonated to give novel ambident carbanions. The
Phase-Transfer Catalyzed Asymmetric [4 + 1] Annulations for the Synthesis of Chiral 2,2-Disubstituted Tetrahydrothiophenes
作者:Qi Yin、Xiaolu Wen、Yiwei Chen、Xiangnan Gong、Lin Hu
DOI:10.1021/acs.orglett.1c02744
日期:2021.10.1
An efficient catalyticasymmetric [4 + 1] reaction, which features the use of simple β-keto esters as one-carbon nucleophiles and 5-succinimidothio-pent-2-enoates as four-atom bielectrophiles, has been developed in the presence of a bifunctional chiral phase-transfer catalyst. The new annulation provides a distinct protocol to access the functionalized 2-acyl-2-carboxyl tetrahydrothiophenes bearing
A series of 4-aryl-4, 7-dihydrothieno [2, 3-b] pyridine-5-carboxylate derivatives (I) was synthesized and tested for binding affinity to Ca2+ channels in rat cerebral cortex membranes, coronary vasodilator effect in isolated guinea pig hearts, and antihypertensive activity in spontaneously hypertensive rats.Several compounds had potent coronary vasodilator and antihypertensive activities.The structure-ctivity relationships of the series indicated that a lipophilic 3-alkyl substituent with moderate bulkiness was effective for enhancing the pharmacological potencies.Among them, methyl 4, 7-dihydro-3-isobuty1-6-methy1-4-(3-nitrophenyl) thieno [2, 3-b] pyridine-5-carboxylate (S-312) was selected as a promising cardiovascular agent.The relationship between the absolute configuration of S-312 and its biological activities is also presented.
Synthesis of 3-Acylpyrroles, 3-(Alkoxycarbonyl)pyrroles, 1,5,6,7-Tetrahydro-4H-indol-4-ones and 3-Benzoylpyridines Based on Staudinger-Aza-Wittig Reactions of 1,3-Dicarbonyl Compounds with 2- and 3-Azido-1,1-dialkoxyalkanes
The Staudinger-aza-Wittig reaction of 1,3-dicarbonyl compounds with 2-azido-1,1-diethoxyethane and subsequent cyclization allowed an efficient synthesis of a variety of pyrroles, 1,5,6,7-tetrahydro-4H-indol-4-ones, and of a pyridine. cyclization - N-heterocycles - pyrroles - azides