CHEMICAL PROCESS

The invention relates to a novel process for the preparation of 13,14-dihydro-15(R)-17-phenyl-18,19,20-trinor-PGF2 alpha isopropyl ester of formula (I), wherein R stands for saturated or unsaturated straight, branched or cyclic C1-7 alkyl or phenyl or benzyl group. The process of the invention comprises reducing the oxo group on the side chain of the compound of formula (VII), transforming the obtained 3,3a,4,5,6,6a-hexahydro-2-oxo-4-[5'-phenyl-3'(R)-hydroxypent-1'-enil]- 5-(4'-phenylbenzoxyloxy)-2H-cyclopenta[b]furan of formula (VI) by hydrogenation to 3,3a,4,5,6,6a-hexahydro-2-oxo-4-[5'-phenyl-3'(R)-hydroxy-1'-pentyl]-5- (4'-phenylbenzoyloxy)-2H-cyclopenta[b]furan of formula (V) reducing the compound of formula (V) to 3,3a,4,5,6,6a-hexahydro-2-hydroxy-4-[5'-phenyl-3'(R)-hydroxy-1'-pentyl ]-5-(4'-phenylbenzoyloxy)-2H-cyclopenta[b]furan of formula (IV), removing the protective group from the compound of formula (IV) to obtain 3,3a,4,5,6,6a-hexahydro-2,5-dihydroxy-4-[5'-phenyl-3'(R)-hydroxy-1'-pe ntyl]-2H-cyclopenta[b]furan of formula (III) then transforming the compound of formula (III) obtained to 13,14-dihydro-15(R)-17-phenyl-18,19,20-trinor-PGF2 alpha of formula (II) by using 4-carboxybutyl-triphenylphosphonium halide and finally, transforming the compound of formula (II) with a compound of the general formula R-X- wherein R has the same meaning as stated above, X is halogen sulphate, mesyl, tosyl or any suitable group to 13,14-dihydro-15(R)-17-phenyl-18,19,20-trinor-PGF2 alpha esters of general formula (I). Nouveau procédé de préparation de l'ester de 13,14-dihydro-15(R)-17-phényl-18,19,20-trinor-PGF2alpha isopropyle répondant à la formule (I), dans laquelle R représente un groupe alkyle ou phényle ou benzyle C1-7 droit, ramifié ou cyclique et saturé ou insaturé. Le procédé consiste à réduire le groupe oxo sur la chaîne latérale du composé répondant à la formule (VII); à transformer par hydrogénation le composé ainsi obtenu, c'est-à-dire le 3,3a,4,5,6,6a-hexahydro-2-oxo-4-[5'-phényl-3'(R)-hydroxypent-1'-ényl]-5-(4'-phényl-benzoxyloxy)-2H-cyclopenta[b]furane répondant à la formule (VI), de manière à obtenir le 3,3a,4,5,6,6a-hexahydro-2-oxo-4-[5'-phényl-3'(R)-hydroxy-1'-pentyl]-5-(4'-phénylbenzoyloxy)-2H-cyclopenta[b]furane répondant à la formule (V); à reduire le composé de la formule (V) en 3,3a,4,5,6,6a-hexahydro-2-hydroxy-4-[5'-phényl-3'(R)-hydroxy-1'-pentyl]-5-(4'-phénylbenzoyloxy)-2H-cyclopenta[b]furane répondant à la formule (IV); à enlever le gro