Deprotonation from an N-methyl group in 2-[1-(dimethylamino)-1-methylethyl]phenylborane derivatives

Reaction of 2-[1-(dimethylamino)-1-methylethyl]phenyllithiun (Ar*Li) with a trialkyl berate, B(OR)(3), in, the 3:1 ratio gave 1-Ar*-3,4,4-trimethyl-1, 2,3,4-tetrahydro-3,1-benzazaborin. as a major product together. with the co rresponding protonated compound and the boronic acid. The structure of the hetelocyclic compound was determined by X-ray analysis and NMR spectroscopy . This compound is formed via the deprotonation from one of the N-Me groups in. Ar*B-2(OR) by the remaining Ar*Li followed by the facile intramolecula r cyclization between the boron and carbon, atoms.