Formation of 2,3-Dihydrothiophene-3-carboxylates from 2(5H)-Thiophenonesvia Sequential Cyclization and Ring-Opening Reactions of 3-Thiahexa-1,5-dienyl Radicals. Preliminary Communication
作者:Ren� Kiesewetter、Paul Margaretha
DOI:10.1002/hlca.19870700115
日期:1987.2.4
Methyl 4-mercapto-2-alkenoates 1, obtained by irradiation of 2(5H)-thiophenones 2 in MeOH, undergo light-induced S–H bond homolysis to give thio radicals 3 which can be trapped with 2-butyne to afford 3-thiahexa-1,5-dienyl radicals 12. Intermediates 12 undergo selective 1,5-ring closure to allylcarbinyl radicals 18, which cyclize to cyclopropylcarbinyl radicals 19. A novel rearrangement of 19 to 23
甲基-4-巯基-2-烯酸酯1,以2(5照射得到ħ)-thiophenones 2在MeOH中,经受光诱导S-H键均裂,得到硫代基团3可与2-丁炔被截留,得到3- -thiahexa-1,5-dienyl基12。中间体12经历对烯丙基羰基自由基18的选择性1,5-环封闭,其环化成环丙基羰基自由基19。的一种新的重排19至23,标题的直接前体化合物15和17,则发生经由 另外两个开环步骤和一个1,5-闭环步骤。