NMR AND X-RAY-DIFFRACTION STUDIES OF 2 BICYCLIC BORATES CONTAINING CHIRAL BORON AND NITROGEN-ATOMS

Ring closure between the nitrogen and boron atoms during the syntheses of bicyclic organoboron compounds occurs under asymmetric induction, since reactions of optically active N-methyl-N-(1-methyl-2-phenyl-2-hydroxyethyl)glycines with 4-bromophenylboronic acid or with 1,4-phenylenediboronic acid provides the corresponding bicyclic boron derivatives (N → B)-4-bromophenyl[N-methyl-N- (1-(S)-methyl-2-(R)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]boron (3a-3b), (N → B)-4-bromophenyl[N-methyl-N-(1-(S)-methyl-2-(S)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]boron (4a-4b), (N → B)(N′ → B′)-1,4-phenylenebis[N-methyl- N-(1-(S)-methyl-2-(R)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]bis-boron (5) and (N → B)(N′ → B′)-1,4-phenylenebis[N-methyl-N-(1-(S)-methyl-2-(S)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]bisboron (6) in high stereochemical yields. The configuration of the nitrogen and boron atoms in 6 and in (N → B) phenyl[N-methyl-N-(1-(S)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]boron (2) is established by single crystal X-ray diffraction studies. © 1990.