Synthese, Basenaddition und Fragmentierung der 1.3.2-Dioxaborolan-4-one / Synthesis, Addition of Bases, and Fragmentation of 1,3,2-Dioxaborolane-4-ones

Abstract

2,5,5-Triorgano-1,3,2-dioxaborolane-4-ones RB(—O—CO—CXY—O—) (2-6) can be prepared from α-hydroxycarboxylic acids XYC(OH)—COOH and dihalogenoorganoboranes RBHal2. They are much weaker Lewis acids than the 2-organo-1,3,2-dioxaborolane-4,5-diones RB(—O—CO—CO—O—) (1). The compounds 1 give 1:1 adducts with the bases DINO, MANO, PyO, and PSy, respectively; the crystal structure determination of 1f · DINO reveals a simple BO-coordination between the components. On electron impact, the chief fragmentation path is the elimination of CO2 from compounds 1-6. The thermal degradation of 2-6 seems to be rather complicated in the liquid phase but is unique in the gaseous phase forming the compounds (RBO)3, CO, and XYC=O.