Shaik Nowshuddin, A. Reddy
Jan 17, 2011
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Influential Citations
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Journal
Tetrahedron-asymmetry
Abstract
Abstract A simple two step procedure for the synthesis of a dipeptide from N -hydroxy-3-azaspiro[5,5]undecane-2,4-dione (HO-ASUD) activated α-amino acids is described. In presence of DCC, N -hydroxy-3-azaspiro[5,5]undecane-2,4-dione readily esterifies the carboxylic acid group of all the N-protected amino acids to yield crystalline N -hydroxy-3-aza spiro[5,5]undecane-2,4-dione activated carboxy ester. The N -hydroxy-3-aza spiro[5,5]undecane-2,4-dione activated carboxy esters of N-protected amino acids readily condensed with other amino acids and gave a dipeptide. This new method is effective for the DCC coupling of a variety of chiral amino acids without loss of enantiomeric purity. Synthesis of fifteen dipeptides including the hitherto unreported Fmoc- l -Orn(Boc)-Val-OMe, Fmoc- l -Cys(trt)-Gly-OEt and Boc- l -Tyr-Gly-OEt is presented.