Dioxopyrrolines. LV. Stereochemical Pathway of (2+2) Photocycloaddition Reaction of 4,5-Diethoxycarbonyl-1H-pyrrole-2,3-dione to Cycloalkadienes and Cycloalkenes.
作者:Takehiro SANO、Hiroshi ENOMOTO、Kenji YASUI、Yoshie HORIGUCHI、Fumiyuki KIUCHI、Yoshisuke TSUDA
DOI:10.1248/cpb.41.846
日期:——
The photocycloaddition reactions of 4, 5-diethoxycarbonyl-1H-pyrrole-2, 3-dione (6) to cycloalkadienes and cycloalkenes were examined. The addition of cyclopentadiene gave the hydroindole 8a (s+a product) as a major product and the cis-fused cyclobutane 7a (s+s product) as a minor one. In contrast, the addition of cyclohexadiene gave the cyclobutane 7b (s+s product) as a major product and the hydroidole 8b (s+a product) as a minor one. The photocycloaddition of cyclopentene, cyclohexene, and indene proceeded predominantly in an s+s manner to give the cis-syn-cis cyclobutanes, 16, 18, and 19, respectively. The stereochemical results were compared with those of the photocycloaddition reaction of 4-ethoxycarbonyl-5-phenyl-1H-pyrrole-2, 3-dione (1) to the corresponding cyclo-olefins, revealing that the steric relationship of the addends plays an important role in determining the stereochemical pathway of the reaction.
研究了 4,5-二乙氧基羰基-1H-吡咯-2,3-二酮(6)与环烷二烯和环烯的光环加成反应。加入环戊二烯后,主要产物为氢吲哚 8a(s+a 产物),次要产物为顺式融合环丁烷 7a(s+s 产物)。相反,加入环己二烯后,主要产物是环丁烷 7b(s+s 产物),次要产物是氢吲哚 8b(s+a 产物)。环戊烯、环己烯和茚的光环加成主要以 s+s 方式进行,分别得到顺式-顺式-顺式环丁烷 16、18 和 19。将这些立体化学结果与 4-乙氧羰基-5-苯基-1H-吡咯-2, 3-二酮 (1) 与相应的环烯烃的光环加成反应的结果进行了比较,发现加成物的立体关系在决定反应的立体化学途径方面起着重要作用。