Huang X, Sun A
Department of Chemistry, Zhejiang University, Hangzhou, Peoples Republic of China.
J Org Chem. 2000 Oct 6;65(20):6561-5. doi: 10.1021/jo0006977.
Regio- and stereoselectivity in the chloropalladation carbonylation reaction of different acetylenic selenides in the presence of 0.05 equiv of PdCl2 and 3 equiv of cupric chloride under 1 atm of carbon monoxide affording 2-seleno-3-chloroacrylates were investigated. Opposite stereoselectivities were observed with 2-phenylethynyl selenides and 2-alkylethynyl selenides: the reactions of 2-phenylethynyl selenides afforded (E)-2-seleno-3-chloro-3-phenylacrylates, while the reactions of 2-alkylethynyl selenides gave (Z)-2-seleno-3-chloro-3-alkylacrylates. A chloropalladation carbonylation mechanism for this reaction was proposed. The regio- and stereoselective chloropalladation of the carbon-carbon triple bond in acetylenic selenides affords 1-enylpalladium intermediates, in which the palladium atom connects with the carbon atom bonding with the selenium atom. Carbonylation in the presence of an alcohol affords 2-seleno-3-chloroacrylates.
研究了在0.05当量的氯化钯和3当量的氯化铜存在下，不同乙炔基硒化物在1个大气压一氧化碳氛围中的氯钯化羰基化反应生成2-硒基-3-氯丙烯酸酯的区域选择性和立体选择性。对于2-苯基乙炔基硒化物和2-烷基乙炔基硒化物观察到相反的立体选择性：2-苯基乙炔基硒化物的反应生成（E）-2-硒基-3-氯-3-苯基丙烯酸酯，而2-烷基乙炔基硒化物的反应生成（Z）-2-硒基-3-氯-3-烷基丙烯酸酯。提出了该反应的氯钯化羰基化机理。乙炔基硒化物中碳-碳三键的区域选择性和立体选择性氯钯化生成1-烯基钯中间体，其中钯原子与与硒原子相连的碳原子相连。在醇存在下进行羰基化反应生成2-硒基-3-氯丙烯酸酯。
