Sulfuric Acid → 6,7-Difluoro-3-methyl-3,4-dihydro-5-oxa-2a-aza-acenaphthylene-1,2-dione

Participants

Reaction Conditions

Reaction Steps

A solution of 45 mL of 98% sulfuric acid in 18 mL of water is heated to 50° C. to 60° C. and treated portionwise over 30 minutes with 10.5 g (41 mmol) of (7,8-difluoro-3-methyl-2,3-dihydro-1,4-benzoxazin-4-yl)oxoacetaldehyde oxime (Example 29). After the addition is complete, the reaction is heated to 80° C. for 15 minutes and poured onto 200 mL of ice and water. The mixture is stirred until the ice melts and the solid is removed by filtration, washed with water and the wet filter cake is dissolved in dichloromethane. The organic solution is washed with water (2×200 mL), dried (MgSO4), filtered and concentrated in vacuo affording 7.1 g of the title compound, mp 169–171° C.

Provenance & Evidence