Synthesis of substituted pterocarpans

摘要

The present invention provides a method of synthesizing compounds of formula (I): ##STR1## wherein R.sub.1 and R.sub.3 are independently H or (C.sub.1 -C.sub.4)alkyl--O--;PPR.sub.2 is R.sub.5 C(O)-- where R.sub.5 is (C.sub.1 -C.sub.4)alkyl or H; and PPR.sub. 4 is H, (C.sub.1 -C.sub.4)alkyl or (C.sub.5 -C.sub.7) aryl optionally substituted with (C.sub.1 -C.sub.4)alkyl or halo.