Alkynes are fundamental molecular building blocks of great importance in synthetic chemistry and materials science. The efficient construction of alkynyl functionality from widely accessible functional groups is therefore highly valuable. Here we report the development of a modular synthesis of alkynes through reaction of carboxylic esters with lithiated gem-diborylalkanes and aryl triflimides. ¹H, ¹³C and ¹¹B NMR spectroscopic and X-ray crystallographic analyses identify and characterize an intermediate α-boryl lithium enolate, which upon triflation with an aryl triflimide followed by water quenching generates the alkyne product. The developed strategy allows a range of carboxylic acid esters to be converted into both internal and terminal alkynes, within a short reaction time, including the transformation of chiral α-substituted esters into chiral propargyl compounds without racemization. The method has been applied to the synthesis of ¹³C-labelled alkynes, using ¹³C-labelled gem-diborylmethane and ¹³C-labelled carboxylic esters, which enables access to ¹³C-labelled terminal alkyne fragments in drugs and natural products.

炔烃是合成化学和材料科学中非常重要的基本分子结构单元。因此，从广泛可及的官能团中有效构建炔基官能团非常有价值。在这里，我们报告了通过羧酸酯与锂化宝石-二硼基烷烃和芳基三氟甲磺酰亚胺的反应来模块化合成炔烃的进展。¹ H、¹³ C 和¹¹B NMR 光谱和 X 射线晶体学分析确定并表征了一种中间体 α-硼基烯醇锂，其在与芳基三氟甲磺酰亚胺三氟甲磺酸化后水淬生成炔烃产物。开发的策略允许在短反应时间内将一系列羧酸酯转化为内部和末端炔烃，包括将手性 α- 取代的酯转化为手性炔丙基化合物而无需外消旋化。该方法已应用于¹³ C 标记炔烃的合成，使用¹³ C 标记的宝石-二硼基甲烷和¹³ C 标记的羧酸酯，可获得¹³药物和天然产物中 C 标记的末端炔烃片段。