Palladium-Catalyzed C–S Bond Cleavage with Allenoates: Synthesis of Tetrasubstituted 2-Alkenylfuran Derivatives
作者:Quannan Wang、Zhuqing Liu、Jiang Lou、Zhengkun Yu
DOI:10.1021/acs.orglett.8b02253
日期:2018.10.5
Palladium-catalyzed C–S cleavage of tetrasubstituted internal alkene α-oxo ketene dithioacetals was realized with allenoates as the coupling partners, efficiently affording tetrasubstituted 2-alkenylfuran derivatives with excellent regioselectivity under mild conditions. Allenoates acted as C1 synthons in the desulfurative [4 + 1] annulation.
An efficient protocol toward fully substitutedthiophenes and thieno[2,3-b]thiophenes has been developed through CuCl2-catalyzed annulative coupling of S,S-disubstituted enones with diazo compounds under mild conditions. Tetrasubstituted thiophenes and thieno[2,3-b]thiophenes were efficiently accessed by variation of the feed ratio of the reactants in good to excellent yields, respectively. The synthetic
A new general synthesis of 3- and 3,4-substituted 4a–q, 3,4-annelated 7a–d and condensed tricyclic 9a–e thiophenes has been developed through Simmons-Smith reaction on the respective α-oxoketene dithioacetals. Extension of the reaction to α-cinnamoylketene dithioacetals 10a–e and its higher enyl analogs 13a–d, 15a–c gave the corresponding 3-styryl 11a–e and 3-di- and trienyl 14a–d, 16a–c thiophenes
Synthesis of Heterocyclic Ketene<i>N,S</i>-Acetals and Their Reactions with Esters of α,β-Unsaturated Acids
作者:Zhi-Tang Huang、Xian Shi
DOI:10.1055/s-1990-26822
日期:——
Ketene S,S-acetals 2 react with 2-amino-1-ethanethiol to afford the substituted 2-methylenethiazolidines 3. The structure of these products as ketene N,S-acetals is confirmed by spectroscopic data. Compounds 3a-f react with esters of α,β-unsaturated acids to give thiazolo[3,2-a] pyrid-5-one derivatives 4, 6, and 7 through an electrophilic addition and cyclocondensation sequences.