Acetone → 2,3,6,7,8,9-Hexahydro-2,2,6,6,9,9-hexamethyl-4H-naphtho[2,3-b]pyran-4-one

Participants

Reaction Conditions

Reaction Steps

A solution of the above hydroxyacetophenone (1.86 g, 7.5 mmol), pyrrolidine (590 mg, 7.5 mmol), acetone (850 mg, 14.6 mmol), and a catalytic amount of p-TsOH in benzene (650 ml) was heated at reflux for 48 hours. The mixture was cooled to 25° C. and diluted with 1N HCl (35 ml). Aqueous work up (Et2O extraction) gave a yellowish brown solid. Recrystallization from hexane afforded 2,3,6,7,8,9-hexahydro-2,2,6,6,9,9-hexamethylbenzo [g]chromen-4-one (structure 1) as fine white crystals (560 mg, 1.95 mmol, 26%): 1H NMR (400 MHz, CDCl3) δ 7.3 (s, 1H), 6.85 (s, 1H), 2.68 (s, 2H), 1.68 (s, 4H), 1.45 (s, 6H), 1.26 (s, 12H).

Provenance & Evidence