Vinylic Organoboranes. 1. A Convenient Synthesis of Acetylenes via the Reaction of Lithium (1-Alkynyl)organoborates with Iodine

Article abstract of DOI:10.1021/jo00374a002

Lithium (1-alkynyl)organoborates, readily prepared from organoboranes and lithium acetylides, undergo a facile reaction at low temperature with iodine to for internal acetylenes in high yield.Unlike conventional methods for the preparation of acetylenes via nucleophilic displacement, the reaction is applicable to both primary and secondary as well as aromatic and functionally substituted groups.The use of lithium acetylide-ethylenediamine form the formation of the organoborate extends the reaction to terminal acetylenes.This reaction occurs with complete retention of the configuration about the boron-carbon bond.The procedure, with its exceptionally broad applicability, provides a simple, general route to internal and terminal acetylenes.