Esterification of the Wang resin 5 with the monoamide of oxalic acid (oxamic acid, 7) followed by dehydration of the amide function furnishes the resin-bound cyanoformate 9, which can be elaborated by zinc-catalyzed reaction with β-keto esters. The obtained enamino keto diesters 10a-d react with hydrazines affording, after removal from the solid sup-
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