Dicyclohexylcarbodiimide → (Hexahydro-5-oxo-1,4-thiazepin-6-yl)carbamic acid, (1,1-dimethylethyl) ester

Participants

Reaction Steps

N-t-Butoxycarbonyl-S-(2-aminoethyl)-L-cysteine (5.0 g) and N-hydroxysuccinimide (2.6 g) are dissolved in 500 ml of DMF. With cooling in an ice-bath, a solution of dicyclohexylcarbodiimide (4.7 g) in 10 ml of DMF is added dropwise over a period of 15 minutes. The reaction mixture is kept in a 4° room for 10 days. The solvent is then removed by lyophilization. The crude product is extracted into chloroform. Repeated chromatography on silica gel (20:1 chloroform-methanol) affords the pure product (3.1 g). The NMR spectrum is consistent with the assigned structure. A pure sample is obtained by recrystallization (ether-methanol) and analyzes for C10H18N2O3S.

Provenance & Evidence