Abstract: The invention relates to a process for the preparation of Famciclovir, which comprises the preparation of a compound of formula (II) wherein X is a halogen atom by reaction of a compound of formula (III) with a compound of formula (VII) wherein L is a leaving group, in the presence of a catalytic amount of a quaternary ammonium salt, followed by hydrogenation of compound (II) to Famciclovir.

Abstract: A process for the preparation of 1,3a,8-trimethyl-1,2,3,3a,8,8a-hexahydro-pyrrole?2,3-b!indol-5(3aS,8aR)-he ptylcarbamate, of formula (I) ##STR1## by reacting eseroline with heptylisocyanate in the presence of a metal cyanate and of a quaternary ammonium salt, in polar aprotic solvents.

Abstract: A process for the preparation of (-)-eserethole, of formula (I) starting from (+)-eserethole, or from mixtures of (.+-.)-and (-)-eserethole in which the latter enantiomer prevails, by treating (.+-.)-eserethole or mixtures of (+)-and (-)-eserethole enriched in the latter enantiomer, with 0.5-0.7 mole (per mole of the enantiomeric mixture) of a resolution agent, to yield a (-)-eserethole salt less soluble than the corresponding (+)-eserethole salt.

Abstract: Eserethole of formula ##STR1## is prepared from 1,3-dimethyl-5-hydroxy-oxindole compound II which is acylated in the first step to obtain 1,3-dimethyl-5-acyloxyoxindole (III). The product is reacted with chloroacetonitrile to obtain 1,3-dimethyl-3-cyanomethyl-5-acyloxy-oxindole (IV). The 5-acyloxy group is hydrolyzed and the hydroxy group is ethoxylated with ethyl halides or sulfate. Then the product is cyclized by treatment with sodium bis-(methoxy-ethoxy)aluminum hydride, to give O-ethyl-nor-eseroline (VI) and the compound is methylated to give eserethole (VII).