Regioselective Synthesis of Functionalized Dihydropyrones via the Petasis Reaction

A novel synthesis methodology for the construction of
functionalized
dihydropyrones has been developed with amines, glyoxylic acid, and
4-substituted-1,2-oxaborol-2­(5H)-ols from the Petasis
reaction. Mechanistic investigation indicated the intermolecular SN2 cyclization to provide 3,6-dihydro-2H-pyran-2-ones
(3,6-DHP) and 5,6-dihydro-2H-pyran-2-ones (5,6-DHP)
in one step with moderate to excellent yields.

一种基于Petasis反应，以胺类、甘醇酸和4-取代-1,2-氧硼醇-2-(5H)-醇为原料构建功能化二氢吡喃的新颖合成方法已被开发。机理研究表明，分子间的SN2环化反应可一步合成3,6-二氢-2H-吡喃-2-酮（3,6-DHP）和5,6-二氢-2H-吡喃-2-酮（5,6-DHP），并实现中到优的产率。