Studies on Isocyanides and Related Compounds: A Facile Synthesis of 1,6-Dihydro-6-oxopyrazine-2-carboxylic Acid Derivatives via Ugi Four-Component Condensation - Faggi, Cristina; García-Valverde, María; Marcaccini, Stefano; Pepino, Roberto; Pozo, Ma Cruz (Synthesis, 2003)