Organic Synthesis Using 1-Methoxy-1,2,3-Butatrienyltrialkylborates. I. A Convenient Synthesis of 1-Alken-3-ynes

Abstract

Over the last several years, we have been interested in synthetic versatility of unsaturated borate complexes having methoxy group(s) in the molecules.^1–6 For example, we reported that methoxycyclopropanes were obtained from the ate-complexes prepared from B-alkyl-9-BBNs and lithium methoxyallene.¹ The reactions of 1,2-dimethoxyethenyltrialkylborates were noteworthy not only synthetically but also mechanistically because the elimination of methoxy groups was found to be well controlled.^2–5 Now, we wish to report here a synthesis of 1-alken-3-ynes from cumulenic borates with a methoxy group.