Three‐Component Reaction to 1,4,2‐Diazaborole‐Type Heteroarene Systems

Abstract

AbstractThe borane FmesBH2 reacts in a three‐component reaction with an isonitrile and a small series of organonitriles to give rare examples of the class of dihydro‐1,4,2‐diazaborole derivatives. In a related way, annulated BN‐indolizine derivatives became conveniently available, as were dihydro‐1,4,2‐oxaza‐ or thiazaborole derivatives. The nucleophilic framework of a dihydro‐1,4,2‐diazaborole example allowed for an uncatalyzed acylation reaction. It also served as a 1,3‐dipolar reagent and underwent a [3+2] cycloaddition/[4+2] cycloreversion sequence when treated with methyl propiolate to give the respective pyrrole product. The [3+2] cycloaddition product of a dihydro‐1,4,2‐diazaborole derivative with N‐phenylmaleimide was isolated and its heterobicyclo[2.2.1]heptane derived structure characterized by X‐ray diffraction.