Synthesis of 2,4′-disubstituted biphenyls via regioselective electrophilic and nucleophilic addition to the (η5-cyclo- hexadienylidene)2[Cr(CO)3]2 dianion
作者:Sheng Sheng Yang、Bryan T. Dawson、Reuben D. Rieke
DOI:10.1016/s0040-4039(00)92701-1
日期:1991.7
(η5-Cyclohexadienylidene)2[Cr(CO)3]2 dianion (2) reacts regioselectively with primary alkyl bromides to produce an intermediate [μ-6-alkyl-6-(η6-phenyl)(1-5-η5)-cyclohexadienyl]bis- (tricarbonylchromium) anion (3). Treatment of intermediates 3 with cyano-stabilized anions, followed by oxidation with I2, resulted in the formation of 2,4 ′-dlsubstitoted biphenyl compounds in good yield. If the initially
(η 5 -Cyclohexadienylidene)2 [CR(CO)3 ] 2的二价阴离子(2)与伯烷基溴化物反应区域选择性以产生中间[μ-6 -烷基-6-(η 6 -苯基)(1-5-η 5)-环己二烯基]双-(三羰基铬)阴离子(3)。用氰基稳定的阴离子处理中间体3,然后用I 2氧化,以高收率形成了2,4'-dl取代的联苯化合物。如果最初添加的烷基包含一个活化的亚甲基单元,则用LDA处理5最终会导致环环戊烯环产物。