Synthesis and Structure of 5‐Diphenylphosphino‐ acenaphth‐6‐yl Boronic Acid, Related Dialkyl Esters and Boroxine Rings

Abstract The reaction of 5‐Ph 2 P‐Ace‐6‐Li (prepared in situ from 6‐Ph P‐Ace‐5‐Br and n ‐BuLi the presence TMEDA) with B(OMe) 3 B(O i ‐Pr) , respectively, provided boronic esters P‐Ace‐6‐B(OR) ( 1 a R=Me; b R= ‐Pr; Ace=acenaphthyl). Hydrolysis crude mixture afforded acid P‐Ace‐6‐B(OH) ), which crystallizes as hydrogen bonded complex ⋅ TMEDA CHCl . Condensation yielded related boroxine [5‐Ph P‐Ace‐6‐BO] oxidized by air exclusively at one phosphorus atom to give P(O)‐Ace‐6‐BO(5‐Ph P‐Ace‐6‐BO) ] 4 ). new compounds have been analyzed multinuclear NMR‐ IR spectroscopy well X‐ray crystallography.