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Unique Regio- and Stereoselectivity in Pd-Catalyzed Chlorocarbonylation Reaction of 2-Phenylethynyl Selenides and 2-Alkylethynyl Selenides. Highly Stereoselective Synthesis of 2-Seleno-3-chloroacrylates
journal contribution
posted on 2000-09-01, 00:00 authored by Xian Huang, Aiming SunRegio- 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.