Toluene → Ethyl 4-amino-2-cyclopentyl-l-phenylalaninate

Participants

Reaction Steps

According to example 151, 1.65 g of ethyl N-(benzyloxy)carbonyl)2-iodo-4-nitro-L-phenylalaninate was subjected to Heck coupling with 20 mL of cyclopentene using 60 mL of toluene, 0.074 g of Pd(OAc)2, 0.20 g of ti-ortho-tolylphosphine, and 0.51 mL of Et3N. The reaction was carried out at 110° C. for 24 h. Analysis of the crude product by tlc (SiO2, 8:2 hexane:EtOAc) indicated a major product at Rf=0.40 and minor components at Rf=0.38, 0.60, and 0.95. The Rf=0.40 material was isolated by flash chromatography on silica gel (8:2 hexane:EtOAc). This afforded 1.03 g (71%) of the desired olefin mixture as a clear liquid. This material was subjected to catalytic hydrogenation at 45 psi for 18 h using 55 mL of MeOH and 0.25 g of 10% Pd(C). The crude product was purified by flash chromatography (SiO2, 99:1 EtOAc:MeOH) to give 0.56 g (61% for both steps) of ethyl 4-amino-2-cyclopentyl-L-phenylalaninate as a thick transparent oil.

Provenance & Evidence