Synthetic Utility of the Palladium-Catalyzed Coupling Reaction of Acid Chlorides with Organotins

Article abstract of DOI:10.1021/jo00172a038

The palladium coupling of acid chlorides with unsymmetrical organotin reagents R''3SnR' can be carried out in chloroform under mild conditions in high yields to give the ketone RCOR'in which only one of the four organic groups on tin appears in the ketone product.Alkyl partners (R''= methyl or butyl) on tin serve as anchoring groups and do not transfer.When R' is acetylenic, vinyl, aryl, methoxymethylene, allyl, or benzyl, transmetalation takes place preferentially, resulting in coupling with the acyl group from the acid chloride.The reaction is tolerant of functional groups both on the acid chloride and the tin reagent.A palladium-catalyzed coupling reaction of an organotin reagent bearing acrylate functionality with an acid chloride serves as a method to introduce both a ketone and an acrylate functionality into a carbon framework.The coupling reaction of 4-(tert-butyldiphenylsiloxy)pentanoyl chloride with benzyl 3-(tributylstannyl)acrylate gave a 71percent yield of benzyl 7-(tert-butyldiphenylsiloxy)-4-oxo-2-octenoate, a precursor to the macrolide antibiotic pyrenophorin.