5H-Dibenzo[a,d]cyclohepten-5-one → 5-(2,4-bis(1,1-dimethylethoxy)pyrimidin-5-yl)-5H-dibenzo[a,d]cyclohepten-5-ol

Participants

Reaction Conditions

Reaction Steps

To a solution of the product of step (i) (50 g) in dry tetrahydrofuran (11) at -78° C. was added n-butyllithium (69 ml of a 2.5M solution in hexane) dropwise such that the internal temperature of the reaction did not rise above -65° C. After 0.5 hours a solution of 5H-dibenzo[a,d]cyclohepten-5-one (44 g) in tetrahydrofuran (100 ml) was added. The reaction mixture was stirred at -78° C. for three hours and then allowed to warm to room temperature overnight. Saturated aqueous ammonium chloride solution (400 ml) was added and the mixture extracted with ethyl acetate. The organic solution was dried (MgSO4) and evaporated under reduced pressure to give the crude 5-{2,4-bis(1,1-dimethylethoxy)pyrimidin-5-yl)-5H-dibenzo[a,d]cyclohepten-5-ol which was used directly. To a stirred solution of this product and triethylsilane (64 ml) in dry dichloromethane (400 ml) cooled in an ice-bath was added trifluoroacetic acid (150 ml) dropwise over ten minutes. The cooling bath was removed and the solution was stirred at room temperature overnight. Toluene (300 ml) was added and solution was evaporated under reduced pressure. The residue was azeotroped with toluene (3 times). The oil was treated with diethyl ether and the precipitated product collected as a white powder. Yield 44 g.

Provenance & Evidence