M. Naruse

The reaction of lithium trialkylalkynylborate with methanesulphinyl chloride : A novel route to internal acetylenes

Abstract Treatment of lithium trialkylalkynylborates ( 1 ) with methanesulphinyl chloride gives internal acetylenes ( 2 ) in good yields. The reaction proceeds via β-methanesulphinylvinylboranes 3 , followed by cis elimination of methanesulphinyl group and dialkylboron groups. The reaction mixture of B-alkyl-9-BBN and 1-lithio-1-heptyne has been treated with methanesulphinyl chloride to provide mainly a cyclooctane derivative 6 . This finding is explained in terms of the steric factors in the approach of the methanesulphinyl chloride.

The reaction of lithium trialkylalkynylborates : A novel method of synthesizing α,β-unsaturated ketones

Abstract Treatment of lithium trialkylalkynylborates with acetyl chloride gave 2-oxa-3-borolenes (2). The enol borinates were oxidized by Jones reagent to highly substituted α,β-unsaturated ketones (4). The stability of 2 is ascribed to the steric hindrance of the B-alkyl groups and to the resonance contribution of the mesomeric structure 3.

The reaction of lithium trialkylalkynylborate with methanesulphinyl chloride. A novel route to internal acetylenes

Abstract Treatment of lithium trialkylalkynylborates (1) with methanesulphinyl chloride gives internal acetylenes (2) in good yields. The reaction proceeds via β-methanesulphinylvinylboranes 3, followed by cis elimination of methanesulphinyl group and dialkylboron groups. The reaction mixture of B-alkyl-9-BBN and 1-lithio-1-heptyne has been treated with methanesulphinyl chloride to provide mainly a cyclooctane derivative 6. This finding is explained in terms of the steric factors in the approach of the methanesulphinyl chloride.