Synthesis of α,α-disubstituted-β-aminoacids with axial chirality

6-aminomethyl-6,7-dihydro-5H-dibenzo[a,c]cycloheptene-6-carboxylic acid ethyl ester H-beta(2)-Bip-OEt 1a and its 1,1'-binaphthyl optically pure analog (R) H-beta(2)-Bin-OEt 2a have been readily synthesized by bis-alkylation of ethyl cyanoacetate with 2,2'-bis-(bromomethyl)-1,1'-diphenyl or optically pure (+)-(R)-2,2'-bis-(bromomethyl)-1,1'-binaphthyl, followed by NaBH4/CoCl2 selective reduction of the cyano group. The N-Boc protected derivatives and short peptides of these novel aminoacids have also been prepared (C) 1998 Elsevier Science Ltd. All rights reserved.