The present invention discloses a process for the preparation of 16, 17-acetals of pregnane derivatives having formula I

##STR00001##

wherein each substituent is independently selected from; R.sub.1 is H or CH.sub.3; R.sub.2 is C.sub.1-C.sub.6 linear or branched alkyl, alkynyl group or cycloalkyl group; aryl or heteroaryl group; or R.sub.1 and R.sub.2 combine to form saturated, unsaturated C.sub.3-C.sub.6 cyclic or heterocyclic ring; R.sub.3 and R.sub.4 are same or different and each independently represents H or halogen; R.sub.5 is —OH or —OCOR wherein R represents H or C.sub.1-C.sub.6 linear, branched or cyclic alkyl group that may be substituted.

Disclosed in the present disclosure is a method for preparing 16alpha-hydroxyprednisolone, belonging to the technical field of medicine preparation and processing. In the method, 21-hydroxypregna-1,4,9(11),16-tetraene-3,20-dione-21-acetate is used as a starting material, and subjected to oxidation, bromo-hydroxylation, debromination and alcoholysis, so as to prepare 16alpha-hydroxyprednisolone. The method for preparing 16alpha-hydroxylprednisolone of the present disclosure can effectively control the generation of impurities in the reaction process by improving the disadvantages of traditional processes, and has a mild reaction process and a high overall conversion rate; and the method of the present disclosure has low requirements for a reaction device and low operation costs, is easy to operate, is suitable for industrial production, and has a good market prospect.

Disclosed in the present disclosure is a method for preparing 16alpha-hydroxyprednisolone, belonging to the technical field of medicine preparation and processing. In the method, 21-hydroxypregna-1,4,9(11),16-tetraene-3,20-dione-21-acetate is used as a starting material, and subjected to oxidation, bromo-hydroxylation, debromination and alcoholysis, so as to prepare 16alpha-hydroxyprednisolone. The method for preparing 16alpha-hydroxylprednisolone of the present disclosure can effectively control the generation of impurities in the reaction process by improving the disadvantages of traditional processes, and has a mild reaction process and a high overall conversion rate; and the method of the present disclosure has low requirements for a reaction device and low operation costs, is easy to operate, is suitable for industrial production, and has a good market prospect.

The present invention further provides method of preparing nanocrystals or microcrystals of a hydrophobic therapeutic agent such as fluticasone or triamcinolone, pharmaceutical compositions (e.g., topical or intranasal compositions) thereof and methods for treating and/or preventing the signs and/or symptoms of disorders such as blepharitis, meibomian gland dysfunction or skin inflammation or a respiratory disease (e.g., asthma).

The present invention discloses a process for the preparation of pregnadiene derivatives having formula I, their stereoisomer and intermediate thereof. Formula I wherein each substituent is independently, R.sub.1 and R.sub.2 is hydrogen or C.sub.1-C.sub.8 straight, branched alkyl chain, saturated or unsaturated cycloalkyl; R.sub.3 is hydrogen or wherein R.sub.5 represents C.sub.1-C.sub.8 straight, branched alkyl chain or cycloalkyl; R.sub.4 is hydrogen or halogen; R.sub.6 is hydrogen or halogen; ##STR00001##

The present invention discloses a process for the preparation of pregnadiene derivatives having formula I, their stereoisomer and intermediate thereof. Formula I wherein each substituent is independently, R.sub.1 and R.sub.2 is hydrogen or C.sub.1-C.sub.8 straight, branched alkyl chain, saturated or unsaturated cycloalkyl; R.sub.3 is hydrogen or wherein R.sub.5 represents C.sub.1-C.sub.8 straight, branched alkyl chain or cycloalkyl; R.sub.4 is hydrogen or halogen; R.sub.6 is hydrogen or halogen;

##STR00001##

The present invention discloses a process for the preparation of 16, 17-acetals of pregnane derivatives having formula I ##STR00001##
wherein each substituent is independently selected from; R.sub.1 is H or CH.sub.3; R.sub.2 is C.sub.1-C.sub.6 linear or branched alkyl, alkynyl group or cycloalkyl group; aryl or heteroaryl group; or R.sub.1 and R.sub.2 combine to form saturated, unsaturated C.sub.3-C.sub.6 cyclic or heterocyclic ring; R.sub.3 and R.sub.4 are same or different and each independently represents H or halogen; R.sub.5 is OH or OCOR wherein R represents H or C.sub.1-C.sub.6 linear, branched or cyclic alkyl group that may be substituted.