Oxalyl chloride → 4H-[1]-Benzothiopyrano[4,3-b]furan-2,3-dione

Participants

Reaction Steps

To a stirred mixture of 4-[trimethyl[silyl]oxy]-2H-benzothiopyran (380.5 g, 1.609 mol), prepared according to the method of L. Hellberg et al, Tet. Letters, 3553-3554 (1974), and one liter of diethyl ether, were added 103.8 g (0.818 mol) of oxalyl chloride in a dropwise manner over a period of 50 minutes at room temperature under nitrogen. The mixture was stirred at room temperature for 17 hours after which time the ether was removed under reduced pressure. The residue was triturated with isopropyl ether/hexane to give 146.9 g (82.3%) of a brown crystalline solid, mp 156° C. (dec).

Provenance & Evidence