Trifluoroacetic acid → (4aR,11bR)-3,3,11b-trimethyl-4,4-dioxo-5,6-dihydro-4aH-[1]benzoxepino[4,5-b][1,4]thiazine-2,10-diamine

Participants

Reaction Steps

A solution of tert-butyl ((4aR,11bR)-10-amino-3,3,11b-trimethyl-4,4-dioxido-4a,5,6,11b-tetrahydro-3H-benzo[6,7]oxepino[4,5-b][1,4]thiazin-2-yl)carbamate (intermediate 19) (308 mg, 0.727 mmol) in DCM (5.5 ml) was treated with trifluoroacetic acid (2.70 ml, 36.4 mmol) for 15 min. The mixture was concentrated, redissolved in DCM, diluted with water and free-based with a saturated solution of NaHCO3. The mixture was extracted with DCM, organic extract was washed with brine, filtered through pad of celite and concentrated to afford (4aR,11bR)-3,3,11b-trimethyl-4,4-dioxo-5,6-dihydro-4aH-[1]benzoxepino[4,5-b][1,4]thiazine-2,10-diamine (180 mg, 0.557 mmol, 77% yield) as an off-white solid. LC/MS (ESI+) m/z=324.2 (M+H).

Provenance & Evidence