A suspension of zinc (0.874 g) in THF with dibromoethane (0.02 mL) was sonicated at 40° C. for 40 minutes under argon. N-Boc-iodo-L-alanine benzyl ester (4.20 g, 10.4 mmol) and dimethylacetamide (5 mL) were added, and the mixture was heated at 55° C. for 1 hour. tbutyl 1-(4-iodophenyl)cyclopropane-1-carboxylate (3.26 g, 9.48 mmol) in dimethylacetamide (10 mL) was added followed by tris(dibenzylideneacetone)dipalladium(0) (0.33 g) and tri-o-tolylphosphine (0.398 g). Heating was continued under argon for 16 hours. The mixture was diluted with ethyl acetate, washed with water, dried, filtered and evaporated. Chromatography of the residue over silica gel (methylene chloride/hexane 1/3 to methylene chloride/ethyl acetate 95/5) gave 2-(S)-tbutoxycarbonylamino-3-[4′-1″-tbutoxycarbonyl)cyclopropyl]benzenepropanoic acid benzyl ester (3.15 g, 6.36 mmol, 67%).
