Synergistic visible-light/Brønsted-acid promoted deconstructive aminoalkylation of spiro dihydroquinazolinones: modular synthesis of α-functionalized unnatural amino acids

Abstract

Synergistic visible-light/Brønsted-acid promoted deconstructive aminoalkylation of spiro-dihydroquinazolinones with aromatic amines and ethyl glyoxylate is presented. The photocatalyst-free protocol delivers a variety of unnatural N-aryl α-amino esters containing a quinazolin-4(3H)-one fragment in good yields with broad functional-group tolerance. Mechanistic studies reveal that the phosphoric acid–aldimine complex, formed in situ, acts both as a single-electron oxidant and as a key participant in this transformation.