The development of an approach toward sterically-hindered chiral 2′-aryl-1,1′-binaphthalenes functionalized at position 2
作者:Michaela Mešková、Martin Putala
DOI:10.1016/j.tetlet.2011.08.046
日期:2011.10
Several approaches were examined for the preparation of 1,1'-binaphthalene derivatives bearing sterically demanding ortho-substituted aryl at position 2' which are suitable for further functionalization at position 2. Steric hindrance of ortho-substituted aryl groups was critical for the approach through BINOL monotriflate. Among variations of cross-coupling reactions of 2,2'-dihalo-1,1'-binaphthalenes, Negishi arylation of an enantiopure 2,2'-dibromide was found to be the method of choice for regioselective and stereoconservative preparation of the target 2'-monoarylated precursor. Functionalization of the latter at position 2 was demonstrated by bromine substitution via lithiation followed by the reaction with several electrophiles. (C) 2011 Elsevier Ltd. All rights reserved.