Phosphine-catalyzed intramolecular γ-umpolung addition of α-aminoalkylallenic esters: facile synthesis of 3-carbethoxy-2-alkyl-3-pyrrolines

摘要

An array of N-tosylated a-aminoalkylallenic esters was prepared and their cyclization under the influence of nucleophilic phosphine catalysts was explored. The a-aminoalkylallenic esters were prepared through aza-Baylis-Hillman reactions or novel DABCO-mediated decarboxylative rearrangements of allenylic carbamates. Conversion of these substrates to 3-carbethoxy-2-alkyl-3-pyrrolines was facilitated through Ph_3P-catalyzed intramolecular γ-umpolung addition.