A new type of functional group differentiation in palladium-catalyzed reactions

✍ Scribed by Godson C. Nwokogu

• Book ID: 104233725
• Publisher: Elsevier Science
• Year: 1984
• Tongue: French
• Weight: 183 KB
• Volume: 25
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)81358-7

✦ Synopsis

Products of palladium-catalyzed ethynylations of various 2-bromoallyl acetates show that the formation of a-vinylpalladium intermediates, instead of a-allylpalladium complexes, is preferred in such substrates. Palladium-catalyzed nucleophilic alkylations of simple ally1 acetates by way of a-allylpalladium complexes' and the coupling of aryl or vinyl halides with nucleophiles through a-vinylpalladium intermediates2 are well-known reactions. For 2-haloallyl acetates (e.g. 1, Scheme 1) which bear both the ally1 acetate and vinyl bromide moieties such that they affect each other, palladium-catalyzed reaction could lead to any or all of the product types 2, 3 or 2 through the two probable reaction pathways a and b. We did not find any previous report concerning this type of chemoselectivity in palladium-catalyzed reactions of substrates like 1 _* OAc b I Br Pd(0) 1 '. Path b Nu Br N"-t 0 I 2 _ AC ; & 1 3 pd-Br I L NuH Base b Scheme We report here that various 2-bromoallyl acetates, under palladium-catalyzed reaction conditions, reacted with acetylenes according to path b only. No product types expected from