A <i>N</i>-Phosphinoamidinato NHC-Diborene Catalyst for Hydroboration

The use of the N-phosphinoamidinato NHC-diborene catalyst 2 for hydroboration is described. N-phosphinoamidine tBu2PN(H)C(Ph)?N(2,6-iPr2C6H3) was reacted with nBuLi in Et2O to afford lithium derivative, which then treated B2Br4(SMe2)2 toluene form N-phosphinoamidinate-bridged diborane 1. It N-heterocyclic carbene IMe (:C{N(CH3)C(CH3)}2) and excess potassium graphite at room temperature give compound 2. can stoichiometrically activate ammonia-borane carbon dioxide. also showed catalytic capability. A mol % portion catalyzed dioxide (CO2) pinacolborane (HBpin) deuterated benzene (C6D6) 110 °C (conversion >99%), afforded methoxyborane [pinBOMe] (yield 97.8%, TOF 33.3 h-1) bis(boryl) oxide [(pinB)2O]. In addition, 5 N-formylation secondary primary amines by yield N-formamides (average 91.6%, 25.9 h-1). Moreover, chemoselectivity toward carbonyl compounds. mechanistic studies, B?B double bond activated substrates, intermediates underwent products regenerate