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
A Novel Route to Stilbenes<i>via</i>Cationic Cycloaromatization
作者:C. V. Asokan、H. Ila、H. Junjappa
DOI:10.1055/s-1987-27919
日期:——
A novel route for substituted stilbenes 3a-j is developed by cationic cycloaromatization of the corresponding (α-allyl-α-hydroxycinnamyl)-ketene dithioacetal derivatives 2a-j in the presence of ether-boron trifluoride complex. The hydroxydithioacetals 2a-j were obtained by 1,2-addition of allyl or crotyl magnesium bromide with the respective styryl β,β-bis(methylthio)vinyl ketones 1a-j.
Reformatskii reaction on .alpha.-oxo ketene dithioacetals: synthesis of substituted and fused ethyl 2-hydroxy-6-(methylthio)benzoates, 6-(methylthio)pyran-2-ones, and 6-(methylthio)-2(1H)pyridone derivatives