Synthesis of cholesterol and vitamin D3 from phytosterols

A process for manufacture of cholesterol from phytosterols, which comprises;

• treating a phytosterol with a p-toluene sulfonyl halide in a first base to obtain a phytosteryl tosylate;
• treating the phytosteryl tosylate with methanol in a second base to obtain a phytosteryl-i-methyl ether;
• treating the phytosteryl-i-methyl ether with ozonized oxygen in a first solvent at a temperature range of −50° C. to −90° C., followed by treatment with a reducing agent at a temperature range of −40° C. to 0° C. to obtain (20S)-20-hydroxymethyl-6β-methoxy-3α,5-cyclo-5α-pregnane;
• tosylating the (20S)-20-hydroxymethyl-6β-methoxy-3α,5-cyclo-5α-pregnane with a tosylating agent in a third base to obtain (20S)-6-methoxy-20-(p-toluene sulfonoxy methyl)-3α,5-cyclo-5α-pregnane;
• subjecting the (20S)-6-methoxy-20-(p-toluene sulfonoxy methyl)-3α,5-cyclo-5α-pregnane to a Grignard reaction by treatment with a reaction product of magnesium and isopentyl bromide in a first ether solvent in the presence of a CuBr·Me2S catalyst to obtain i-cholesteryl methyl ether;
• and
• hydrolyzing the i-cholesteryl methyl ether in aqueous dioxane with catalytic amounts of PTSA at a temperature of 70-90° C. to obtain cholesterol.