An efficient synthesis of tetrasubstituted cyclohexyl-1,2-diamines
摘要:
The synthesis of symmetrically tetrasubstituted diamines derived from the (R,R)-cyclohexyl-1,2-diamine is reported. We comment on the efficiency of this sequential substitution approach as a method for the synthesis of tetrasubstituted diamines and discuss the acceptable substitution pattern for this methodology. (C) 2005 Elsevier Ltd. All rights reserved.
Enantioselective addition of methyllithium to aromatic imines catalyzed by C2 symmetric tertiarydiamines is described. Eleven diamines have been tested, for which dramatic effect of the nitrogen substitution has been observed. Diamines bearing hindered group close to the nitrogen led to racemic product while homologous hindered diamines led to the best results. Enantiomeric excess up to 74% could
New chiraldiamines were prepared, based on the cyclohexane diamine core. The two different substituents on each nitrogen allow this heteroatom to become a stereogenic center upon chelation with a metal, such as lithium. The enantioselective addition of MeLi to imines, with ee's up to 68%, illustrates the validity of this concept.
Synthesis of N,N′-disubstituted cyclic 1,2-diamines derived from (1R,2R)-1,2-diaminocyclohexane
作者:Ewan Boyd、Gregory S. Coumbarides、Jason Eames、Ray V.H. Jones、Majid Motevalli、Rachel A. Stenson、Michael J. Suggate
DOI:10.1016/j.tetlet.2005.03.128
日期:2005.5
The synthesis of N,N'-unsymmetrically tetrasubstituted cyclic 1,2-diamines derived from (IR,2R)-diaminocyclohexane is reported. We comment on the structural nature of these cyclic 1,2-diamines and discuss their characteristic features. (c) 2005 Elsevier Ltd. All rights reserved.