Synthesis and characterization of (N -> B) phenyl[N-alkyl-N-(2-alkyl) aminodiacetate-O,O ',N]boranes and phenyl[N-alkyl-N-(2-alkyl) aminodiacetate-O,O ',N]boranes

摘要

The reaction of boron heterocycles 1 and 2 with n-butyl lithium and alkyl halides led to (N -> B) phenyl[N-alky-N-(2-alkyl)aminodiacetate- O, O',N]boranes 3-6(a-b), 7(b) and 9(b), where alkyl can be in exo and/or endo position, and phenyl[N-alkyl-N-(2-alkyl)aminodiacetate-.O,O',N]boranes 7(c) and 8(c) isomers, which do not display the intramolecular N -> B coordination bond. The existence of steric interactions between N-benzyl and the alkyl group at 2 position was indicated by H-1 and C-13 NMR, while, the delta(B-11) values confirm the tetrahedral and trigonal environment of the B-11 nucleus in these compounds. Moreover, the compounds were characterized by COSY, HETCOR and homonuclear proton decoupling experiment. The study of the intramolecular N -> B coordination by dynamic NMR afforded a Delta G double dagger value of 81.09 kJ/mol for compound 6(b). (c) 2006 Elsevier Ltd. All rights reserved.