Process for the production of 16,17-[(cyclohexylmethylen)bis(oxy)]-11,21-dihydroxy-pregna-1,4-dien-3,20-dion or its 21-isobutyrat by transketalisation
View Patent ↗The invention relates to a process for the preparation of 16,17-[(cyclohexylmethylene)bis(oxy)]-11,21-dihydroxypregna-1,4-diene-3,20-dione[11β,16α(R)] and similar compounds, by reaction of an appropriate 16,17-ketal with cyclohexanealdehyde.
1. A process for the preparation of a compound of the formula 1
in which
R is hydrogen (H), in over 95% epimerically pure form, wherein compounds of the formula 2
in which R is hydrogen (H), R1 is methyl (CH3) and R2 is methyl (CH3),
are reacted with cyclohexanealdehyde using perchloric acid as a catalyst and a nitrated hydrocarbon as a solvent at a temperature between 0° C. and 40° C.
2. The process as claimed in claim 1 , wherein the solvent is nitromethane, 2-nitropropane or 1-nitropropane.
3. The process according to claim 1 , wherein the solvent is 1-nitropropane.
4. The process according to claim 1 , wherein the perchloric acid is 60% to 70% in strength.
5. The process according to claim 1 , wherein the compound of the formula 1 is 16,17-[(Cyclohexylmethylene)bis(oxy)]-11,21-dihydroxypregna-1,4-diene-3,20-diene[11β,16α(R)].