Barbituric Acid → (2R,4S,4aS)-rel-11-fluoro-2,4,8-trimethyl-1,2,4,4a-tetrahydro-2'H,6H-spiro[isoxazolo[4,5-g][1,4]oxazino[4,3-a]quinoline-5,5'-pyrimidine]-2',4',6'(1'H,3'H)-trione

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 6-((2R,6S)-2,6-dimethylmorpholino)-7-fluoro-3-methylbenzo[d]isoxazole-5-carbaldehyde (Intermediate 34, 543 mg, 1.86 mmol) in isopropanol (50 ml) was added pyrimidine-2,4,6(1H,3H,5H)-trione (238 mg, 1.86 mmol), and the reaction mixture was stirred for 16 hours at 80° C. Solvent was removed and the residue was triturated with isopropanol. The solid was filtered, washed with isopropanol, and dried in vacuo. The filtrate was concentrated and purified on silica gel (30-50% EtOAc in hexanes). The product thus obtained was combined with the filtered solid in methanol and concentrated to give the title compound (528 mg, 71%) as a racemic mixture.

Provenance & Evidence