CHOLESTERYL PHOSPHITE AND RELATED COMPOUNDS

Abstract

The preparation of cholesteryl phosphorodichloridite (2) is described; this compound with aniline (2 mol. equiv.) gave the N-phenylphosphoramidochloridite (5) and the latter by condensation with water afforded the N-phenyl-amidophosphite (6).

Similarly the N-phenylphosphoramidochloridite (5) with morpholine gave the morpholidite (7); phenylhydrazine gave the hydrazinophosphite (8) and ethanol the amidoethyl phosphite (9). Cholesteryl phosphorodichloridite (2) by reaction with aniline (4 mol. equiv.) gave the N,N ¹?diphenylphosphorodiamidite (10).

The reaction of cholesteryl phosphorodichloridite (2) with methanol and ethanol are discussed in relation to the analogous reactions with cholesteryl phosphorodichloridate. Boiling ethanol gave cholesterol as the only isolatable product but at room temperature a low yield of the diethylphosphite (11; R=Et) was obtained. The yield of the phosphite was greatly increased in the presence of base. Similarly the dichloridite 2 with boiling water gave cholesterol (1), but at room temperature cholesteryl phosphite 3 was isolated: the mechanistic basis for these different results is briefly discussed.

trans-4-t-Butylcyclohexanol with phosphorus trichloride gave the phosphorodichloridite, which was characterised by conversion to the corresponding N,N ¹?diphenylphosphorodiamidite.