... A solution of the residue in EtOAc was extracted with 10% NaHCO,, and the aqueous phase reextracted with EtOAc (2 x ) The combined organic phases were ... 9.79 (brs, lH;CSNH,);"CNMR([ D,]DMSO):6 = 28.1 (Boc-CH,).37.4(CH2),78.5 (Boc-C,). 140.9 (C&,J, 143.7 (C&J. ... Chem. ...