From Cycloalkanols to Heterocycles via Nitrogen Insertion
作者:Alexander Sandvoß、Johannes M. Wahl
DOI:10.1021/acs.orglett.3c02048
日期:2023.8.11
transition-metal-free nitrogen insertion provides access to a variety of medicinally relevant heterocycles such as pyrrolidenes, quinolines, and benzazepines (24 examples). Furthermore, combination with a photochemical Norrish–Yang-type cyclization allows an unprecedented access to indoles from ortho-substituted acetophenones.
Catalytic Asymmetric Hydrogenation of Imines with a Chiral Titanocene Catalyst: Scope and Limitations
作者:Christopher A. Willoughby、Stephen L. Buchwald
DOI:10.1021/ja00099a012
日期:1994.10
The asymmetric hydrogenation of imines with a chiral titanocene catalyst derived from Brintzinger's ansatitanocene complex 1 proceeds to afford amines with good to excellent enantioselectivity. The catalyst is particularly effective for the reduction of cyclic imines. For these substrates enantiomeric excesses from 95 to 99% were achieved. For acyclic imines lower enantiomeric excesses were observed. The reason for this is likely due to the fact that the acyclic imines are mixtures of anti and syn isomers which interconvert during the reaction. The catalyst was found to be tolerant of many functional groups found in organic synthesis. Thus the reaction represents an effective method for the synthesis of chiral cyclic amines.
GIOVANNINI, ARIANNA;SAVOIA, DIEGO;UMANI-RONCHI, ACHILLE, J. ORG. CHEM., 54,(1989) N, C. 228-234