Phosphoric Acid → Dicyclohexylamine

Participants

Reaction Conditions

Reaction Steps

To a mixture of 3.5 g of orthophosphoric acid in 33 mL of acetonitrile were added 2.2 g of tri-n-butylamine and 3.3 g of molecular sieves 4A, and the mixture was cooled to 5° C. with stirring. To the mixture was added 3.28 g of 5-O-(4-chlorobenzoyl)-2,3-dideoxy-α-D-ribosyl chloride. After 1 hour, precipitation of crystals initiated and then a thick suspension was provided. After 20 hours, the ratio of α-form/β-form for compound (23) in the reaction suspension was 10:1. To the suspension was added 6.5 g of tri-n-butylamine to dissolve the precipitated crystals and molecular sieves were removed by filtration. The filtrate was diluted with 70 mL of toluene and then washed with 55 mL of water. The organic layer was ice-cooled. To the mixture was added 2.5 g of cyclohexylamine for crystallization with stirring. After 1 hour, the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 4.56 g of a dicyclohexylamine salt of compound (23) as a colorless powder (Yield: 71.5%; α-form:β-form=97:3).

Provenance & Evidence