5-Bromo-2,4-bis(1,1-dimethylethoxy)pyrimidine → (+/-)-5-(2-Ethyl-7-methyl-4H-benzo[5,6]cyclohepta[1,2-d]oxazol-4-yl)-2,4(1H,3H)-pyrimidinedione

Participants

Reaction Steps

To a solution of the product of step (vi) (1.74 g) in dry tetrahydrofuran (20 ml) at −78° C. was added n-butyllithium (2.3 ml of a 2.5M solution in hexanes) dropwise. After 0.5 hours a solution of the product from step (v) (1.26 g) in tetrahydrofuran (10 ml) was added. The reaction mixture was allowed to warm to room temperature and saturated brine was added. The mixture was extracted with ethyl acetate, the organic phase was dried (MgSO4) and the solvent was evaporated under reduced pressure. The residue was dissolved in acetic acid (20 ml) and the solution was heated at reflux for 64 hours. The solvent was evaporated under reduced pressure and the residue was then dissolved in trifluoroacetic acid (20 ml) and the solution heated at reflux for 64 hours. The solvent was evaporated under reduced pressure. Purification was by trituration with diethyl ether and filtration.

Provenance & Evidence