A compound has the formula 1
in racemic form, enantiomerically enriched form or enantiomerically pure
form. R.sup.6 is preferably --Si(R.sup.8R.sup.9R.sup.10) or
--(R.sup.7)Si(R.sup.8R.sup.9R.sup.10), wherein R.sup.7 is an alkylene
group, an alkenylene group, or an alkynylene group; and R.sup.8, R.sup.9
and R.sup.10 are independently a C.sub.1-10 alkyl group, a C.sub.2-10
alkenyl group, a C.sub.2-10 alkynyl group, an aryl group or a
--(CH.sub.2).sub.NR.sup.11 group, wherein N is an integer within the
range of 1 through 10 and R.sup.11 is a hydroxy group, alkoxy group, an
amino group, an alkylamino group, a dialkylamino group, a halogen atom, a
cyano group, --SR.sup.c or a nitro group. R.sup.1-R.sup.4 can be broadly
substituted. R.sup.5 is preferably a C.sub.1-10 alkyl group, an alkenyl
group, an alkynyl group, or a benzyl group. R.sup.13 is preferably H, F
or --CH.sub.3. R.sup.16 is R.sup.16 is --C(O)R.sup.f or H. The E-ring
(the lactone ring) may be opened. A method of synthesis of compound (1)
and intermediates in the synthesis thereof are provided.
