The asymmetric ullmann coupling reaction of chiral diol diesters of 1-bromo-2-naphthoic acid and 2-halo-3-nitrobenzoic acids: Highly diastereoselective synthesis of atropisomeric 6,6'-dinitrodiphenic acids1

Abstract

The copper-promoted Ullmann reaction of chiral diol diesters of 1-bromo-2-naphthoic acid induced axial dissymmetry into the newly formed 1,1'-binaphthyl bond: chiral diol, apparent net optical yield for the joining of two naphthyl units, and axial chirality induced are as follows: (S)-1,l'-binaphthyl-2,2'-diol, 71%, S; (1S,2S)-1 ,2-diphenyl-1 ,2-ethanediol, 32%, S; (1R,2R)-1,2-bis(ethoxycarbonyl)-l ,2-ethanediol, 33%, S; (4S,55)-bis(hydroxy-methyl)-2,2-dimethyl-l,3-dioxolane, 3.7%, R. The reaction of (R)-l,l'-binaphthyl-2,2'-diol esters of 2-halo-3-nitrobenzoic acids gave up to 85% net optical yield for the coupling; the intramolecular cyclization proceeded with virtually complete diastereoselectivity to give cyclic diester of R,R-configuration in a 42% isolated yield. This remarkable stereocontrol is ascribed to the steric requirement of the l2-membered cyclic diester structure containing rigid l,1'-binaphthyl and I,1'-biphenyl moiety.