反应详情

The 2-isopropylsuccinic acid 1-ethyl ester was converted into the 4-acid chloride as in Step 2, Example XIII and condensed with 2-phenyl-4-benzyloxazolone, and the resultant product subsequently was decarboxylated and hydrolyzed to 5-benzamido-4-oxo-2-isopropyl-6-phenylhexanoic acid as in Steps 3-4, Example XIII. The intermediate hexanoic acid was condensed with L-proline benzyl ester in a manner similar to Step 8, Example I, Procedure A, except that 1-hydroxybenzotriazole was omitted. The resultant mixture of diastereomeric proline benzyl esters was hydrogenated over 10% palladium-on-carbon in 90% yield to afford 5-benzamido-4-oxo-2-isopropyl-6-phenylhexanoyl-L-proline as a isomeric mixture whose mass spectrum showed a peak at m/e 464 in agreement with the calculated molecular weight. Calcd (C27H32N2O5.H2O) C, 67.2; H, 7.10; N, 5.80. Found: C, 66.8; H, 6.60; N, 5.90.