SYNTHESIS OF 4-OXO-L-PROLINE AND CIS-4-HYDROXY-L-PROLINE DERIVATIVES FROM L-ASPARTIC ACID

When hexafluoroacetone is used to generate a protecting group for L‐aspartic acid, the diazacarbonyl compound 1 can be prepared and subsequently converted into the bicyclic proline derivative 2 with Rh catalysis. Because of the concave shape of 2, new chiral centers can be made with high stereoselectivity; 4‐oxo‐L‐proline, unsubstituted and substituted in the 5 position, cis‐4‐hydroxy‐L‐proline, and other derivatives are readily accessible. R  H, CO2Et. (Figure Presented.) Copyright © 1993 by VCH Verlagsgesellschaft mbH, Germany