A Novel Photoreversible Photochromic System Involving a Hydrogen Transfer/Cyclization Sequence.

A novel photoreversible photochromic system, 3-(2-benzylbenzoyl)-1,2-R,R 1 -4(1H)-quinolinones/12-hydroxy-5-R-5a-R 1 -6-phenyl-5a,6-dihydrobenzo[b]acridin-11(5H)-ones, is described.