A new and expeditious synthesis of all enantiomerically pure stereoisomers of rosaprostol, an antiulcer drug.

Four enantiomerically pure stereoisomers of rosaprostol (), an antiulcer drug, were efficiently synthesized from the enantiomers of 2-(dimethoxyphosphoryl)-3-hexylcyclopentanone () as chiral substrates. The latter were obtained by resolution of racemic with (+)-()-1-(1-naphthyl)ethylamine. The conversion of (+)- into rosaprostol stereoisomer (-)- was accomplished in four steps in 56% overall yield.

Synthesis of Enantiomerically Pure Stereomers of Rosaprostol.

Enantiopure stereomers of rosaprostol 1, an antiulcer drug, were synthesized from diastereomeric building blocks (-)-5a and (+)-5b. Conversion of (-)-5a into rosaprostol stereomer (-)-(1S,2R,5R)-1a was accomplished in nine steps in 18% overall yield. In this sequence, fully diastereoselective hydrogeneration of the endocyclic carbon double bond in the cyclopentenone ring was key, generating a new stereogenic center (C-2 in 1a).

Diphosphine sulfides derived from 2,2'-biphosphole: novel chiral S,S ligands for palladium-catalyzed asymmetric allylic substitution.

Diphosphine sulfides derived from 2,2'-biphosphole have been efficiently synthesized in an enantiomerically pure form by a four step synthetic sequence. These S,S-ligands were used for the first time in Pd-catalyzed asymmetric allylic alkylation. Good yields and enantiomeric excess up to 73% were obtained.