... 0022-2623/91/1834-1721$02.50/0 0 1991 American Chemical Society Page 2. 1722 Journal of Medicinal Chemistry, 1991, Vol. 34, No. 5 Scheme I Larsen et al. 1 base R3X -- 2 0 Table I. Synthesis of 4,5-Dioxopyrrolidine-3-carboxylic Acid, Ethyl Esters 1 ...