Versatile intermediate for annonaceous acetogenins

A process for preparing a compound of formula (I), comprising the steps of:

• (a) reacting a long chain aliphatic aldehyde of the formula (II) ##STR15## with a vinyl magnesium halide to form an allylic alcohol (III):
• ##STR16## (b) reacting the allylic alcohol (III) with triethyl orthoacetate in the presence of a catalytic amount of acid to form a .gamma., .delta.-unsaturated ethyl ester of formula (IV);
• ##STR17## (c) extending the carbon chain of the .gamma., .delta.-unsaturated ethyl ester (IV) to form a compound of formula (VIII):
• ##STR18## (d) converting the allylic alcohol (VIII) to an epoxy alcohol of formula (IX);
• ##STR19## (e) converting the primary alcohol of the epoxy alcohol (IX) to a leaving group (OSO.sub.2 R.sub.2) of formula (X):
• ##STR20## (f) subjecting (X) to Sharpless asymmetric dihydroxylation (ADH) to form the epoxide of formula (XI);
• ##STR21## (g) opening the epoxide ring in the presence of an acid and simultaneously 5-exo cyclization of the epoxide (XI) to form the desired THF unit of formula (XII);
• and ##STR22## (h) treating the THF-containing compound (XII) with base to form the epoxy THF compound of formula (I):
• ##STR23## wherein R is H.sub.2n+1 C.sub.n and n ranges from 1 to 15;
• and R.sub.2 is aryl or alkyl.