TRIMETHYLCHROMENES

Thermal decomposition of 4-(4-hydroxyphenyl)-2,2,4-trimethylchromane ( 1) gives 2,2,4-trimethyl-2H-chromen (2) and 2,2-dimethyl-4-methylenech roman (3). Under influence of hydrochloric acid, 3 isomerizes smoothly to 2. Under similar reaction conditions 2'-hydroxy-2,4,4-trimethylfla van (4) is transformed into 2 and 2,4,4-trimethyl-4H-chromen (5); elim ination of the phenol moiety is accompanied with a rearrangement. open ing of the pyran ring with subsequent re-cyclization seems to be more reliable explanation of this transformation than simple 1-3 migration of the methyl group.