Stereoselective deoxygenation reaction

A process for the preparation of a compound of formula II:

• ##STR83## wherein ##STR84## represents:
• a) 5- or 6-membered heterocyclyl containing one, two or three double bonds, but at least one double bond and 1, 2 or 3 heteroatoms selected from O, N and S, the heterocyclyl is unsubstituted or substituted with one, two or three substituents selected from the group consisting of:
• OH, CO.sub.2 R.sup.4, Br, Cl, F, I, CF.sub.3, N(R.sup.5).sub.2, C.sub.1 -C.sub.8 alkoxy, C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.8 alkynyl, or C.sub.3 -C.sub.8 cycloalkyl, CO(CH.sub.2).sub.n CH.sub.3, and CO(CH.sub.2).sub.n CH.sub.2 N(R.sup.5).sub.2,
• b) 5- or 6-membered carbocyclyl containing one or two double bonds, but at least one double bond, the carbocyclyl is unsubstituted or substituted with one, two or three substituents selected from the group consisting of:
• OH, CO.sub.2 R.sup.4, Br, Cl, F, I, CF.sub.3, N(R.sup.5).sub.2, C.sub.1 -C.sub.8 alkoxy, C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.8 alkynyl, or C.sub.3 -C.sub.8 cycloalkyl, CO(CH.sub.2).sub.n CH.sub.3, and CO(CH.sub.2).sub.n CH.sub.2 N(R.sup.5).sub.2,
• c) aryl, wherein aryl is as defined below,
• C.sub.1 -C.sub.8 alkoxy, C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.8 alkynyl, or C.sub.3 -C.sub.8 cycloalkyl, are unsubstituted or substituted with one, two or three substituents selected from the group consisting of:
• OH, CO.sub.2 R.sup.4, Br, Cl, F, I, CF.sub.3, N(R.sup.5).sub.2, C.sub.1 -C.sub.8 alkoxy, C.sub.3 -C.sub.8 cycloalkyl, CO(CH.sub.2).sub.n CH.sub.3, and CO(CH.sub.2).sub.n CH.sub.2 N(R.sup.5).sub.2,
• aryl is defined as phenyl or naphthyl, which is unsubstituted or substituted with one, two or three substituents selected from the group consisting of:
• OH, CO.sub.2 R.sup.4, Br, Cl, F, I, CF.sub.3, N(R.sup.5).sub.2, C.sub.1 -C.sub.8 alkoxy, C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.8 alkynyl, or C.sub.3 -C.sub.8 cycloalkyl, CO(CH.sub.2).sub.n CH.sub.3, CO(CH.sub.2).sub.n CH.sub.2 N(R.sup.5).sub.2, and when two substituents are located on adjacent carbons they can join to form a 5- or 6-membered ring with one, two or three heteroatoms selected from O, N, and S, which is unsubstituted or substituted with with one, two or three substituents selected from the group consisting of:
• H, OH, CO.sub.2 R.sup.6, Br, Cl, F, I, CF.sub.3, N(R.sup.7).sub.2, C.sub.1 -C.sub.8 alkoxy, C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.8 alkynyl, or C.sub.3 -C.sub.8 cycloalkyl, CO(CH.sub.2).sub.n CH.sub.3, and CO(CH.sub.2).sub.n CH.sub.2 N(R.sup.5).sub.2,
• n is 0 to 5;
• R.sup.1 is:
• a) C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.8 alkynyl, C.sub.3 -C.sub.8 cycloalkyl,
• b) aryl, or
• c) heteroaryl;
• heteroaryl is defined as a 5- or 6-membered aromatic ring containing 1, 2 or 3 heteroatoms selected from O, N and S, which is unsubstituted or substituted with one, two or three substituents selected from the group consisting of:
• OH, CO.sub.2 R.sup.4, Br, Cl, F, I, CF.sub.3, N(R.sup.5).sub.2, C.sub.1 -C.sub.8 alkoxy, C.sub.1 -C.sub.8 alkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.8 alkynyl, or C.sub.3 -C.sub.8 cycloalkyl, CO(CH.sub.2).sub.n CH.sub.3, and CO(CH.sub.2).sub.n CH.sub.2 N(R.sup.5).sub.2,
• R.sup.2 is OR.sup.4 or N(R.sup.5).sub.2 ;
• R.sup.3b is:
• a) C.sub.1 -C.sub.8 alkyl,
• b) aryl, or
• c) heteroaryl;
• R.sup.4 is C.sub.1 -C.sub.8 alkyl;
• and
• R.sup.5 is:
• H, C.sub.1 -C.sub.8 alkyl, or aryl,
• comprising reacting a compound of formula I ##STR85## with a reducing agent and optionally an acid in a solvent at a temperature range of about -78.degree. C. to about 100.degree. C.