Patent ID: 7442799

Claim:
A method for preparing a 2-substituted-5-oxo-3-pyrazolidinecarboxylate compound of Formula I wherein L is H, optionally substituted aryl, optionally substituted tertiary alkyl, —C(O)R 3 , —S(O) 2 R 3 or —P(O)(R 3 ) 2 ; R 1 is an optionally substituted carbon moiety; R 2a is H, OR 4 or an optionally substituted carbon moiety; R 2b is H or an optionally substituted carbon moiety; each R 3 is independently OR 5 , N(R 5 ) 2 or an optionally substituted carbon moiety; R 4 is an optionally substituted carbon moiety; and each R 5 is selected from optionally substituted carbon moieties; comprising: contacting a succinic acid derivative of Formula II wherein X is a leaving group; and Y is a leaving group; with a substituted hydrazine of Formula III LNHNH 2 III in the presence of a suitable acid scavenger and solvent.