BASE-CATALYZED RING OPENINGS OF BENZOCYCLOBUTENONES AND BENZOCYCLOBUTENOLS
BASE-CATALYZED RING OPENINGS OF BENZOCYCLOBUTENONES AND BENZOCYCLOBUTENOLS
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DOI：
10.1139/v95-205
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发表时间：
1995-10-01
期刊：
影响因子：
--
通讯作者：
DURST, T
中科院分区：
文献类型：
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作者：
BRADLEY, JC;DURST, T
本文研究了E-和Z-亚苄基苯并环丁烯酮和醇的碱催化开环反应。C1-C2键的断裂导致形成二苯乙烯，其主要（有时仅）保留立体化学。对于醇，这些结果指向氧阴离子诱导的碳-碳键裂解，导致乙烯基阴离子质子化，在质子溶剂中保留构型，而不是向烷氧基邻醌二甲烷打开电环。亚苄基苯并环丁烯醇的Z异构体与甲基锂在THF中在20 ℃下的反应导致异构化为E异构体、C1-C2键的断裂和所得异构化的乙烯基阴离子的反式异构化。
The base-catalyzed ring opening of a number of isomeric E- and Z-benzylidenebenzocyclobutenones and -ols has been studied in both protic and aprotic solvents. Cleavage of the C1-C2 bond results in the formation of stilbenes with mainly, and at times exclusively, retained stereochemistry. For the alcohols, these results point to an oxyanion-induced carbon-carbon bond cleavage leading to a vinyl anion that is protonated with retention of configuration in the protic solvents rather than to an electrocyclic ring opening to an alkoxy o-quinodimethane. Reaction of the Z isomer of benzylidenebenzocyclobutenol with methyllithium in THF at 20 degrees C causes isomerization to the E isomer, cleavage of the C1-C2 bond, and recyclization of the resultant isomerized vinyl anion.