Unusual Hydroalumination-Bromination Reaction of 1,4-Butynediol

摘要

The hydroalumination-halogenation of propargyl alcohols with a lithium aluminum hydride-iodine or lithium aluminum hydride-pyridinium dibromide system followed by methylation of the obtained vinyl halides with lithium dimethyl copper is used as a convenient method for the synthesis of a variety of natural terpenoid products [1]. For the hydroalumina-tion-bromination 1.2-1.3-fold excess of brominating agent is commonly used. Its residual amount is neutralized with a sodium hydroxide solution [2]. Use of the pyridinium dibromide complex was intended to exclude the electrophilic addition to double bonds [3]. This complex is also known to add to the triple bonds [4].