4-exo-dig cyclocarbopalladation:: A straightforward synthesis of Cyclobutanediols from acyclic γ-bromopropargylic diols under microwave irradiation conditions

Treatment of acyclic gamma-bromopropargylic diols with tributyl-stannylated alkynes under palladium catalysis and microwave irradiation conditions gives high yields of the bis(alkylidene)cyclobutanediol derivatives and cyclobutenediols through an efficient 4-exo-dig cyclocarbopalladation. The cyclization is general with a wide variety of alkyne derivatives and gives access to new cyclobutane ring systems bearing one exocyclic double bond and one eneyne substituent as well as bicyclic dienes sharing a common double bond that may be of interest for further elaborations of complex molecules. (c) Wiley-VCH Verlag GmbH & Co.