A unique family of chiral peraza N 6 -macrocyclic ligands, which are conformationally rigid and have a tunable saddle-shaped cavity, is described. Utilizing their manganese(I) complexes, the first example of earth-abundant transition metal-catalyzed asymmetric formal anti-Markovnikov hydroamination of allylic alcohols was realized, providing a practical access to synthetically important chiral γ-amino alcohols in excellent yields and enantioselectivities (up to 99 % yield and 98 % ee). The single-crystal structure of a Mn I complex indicates that the manganese atom coordinates with the chiral dialkylamine moiety in a bidentate fashion. Further DFT calculations revealed that five of the six nitrogen atoms in the ligand were engaged in multiple noncovalent interactions with Mn, an isopropanol molecule, and a β-amino ketone intermediate via coordination, hydrogen bonding, and/or CH•••π interactions in the transition state, showing a remarkable role of the macrocyclic framework.
An
efficient sequential intramolecular hydroamination/asymmetric
hydrogenation reaction under catalysis of a single chiral ruthenium
complex or a binary system consisting of achiral gold complex and
chiral ruthenium complex has been reported. A diverse range of enantioenriched
benzo-fused N-heterocycles, including 1,2,3,4-tetrahydroquinoline,
indoline, and 2,3,4,5-tetrahydro-1H-benzo[b]azepine derivatives, were obtained from anilino-alkynes
in high yields (up to 98%) with moderate to excellent enantioselectivities
(up to 98% ee) under mild conditions. This protocol features good
functional group tolerance and high atom economy. Furthermore, this
catalytic protocol is applicable to gram-scale synthesis of a naturally
occurring alkaloid, (−)-Angustureine.
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