Abstract: The invention relates to a process for preparing 1-aryl-pyrazol-3-one intermediates, tautomers, and salts thereof, to novel intermediates, and to the use of the intermediates in the preparation of sigma receptor inhibitors.

Abstract: It comprises a preparation process of entecavir comprising: submitting a (1S,3R)-3-(tert-butyldimethylsilyloxy)-1-(oxiran-2-yl)pent-4-yn-1-ol (VIII) to a double esterification and to a radicalary cyclization, yielding a compound of formula (V), where either a compound of formula (VIII) is submitted to a first esterification reaction, then to a catalytic radicalary cyclization using titanocene dichloride as catalyst in the presence of Mn/2,4,6-collidine HCl or Zn/2,4,6-collidine/trimethylsilyl chloride, and finally to a second esterification reaction or, alternatively, the compound of formula (VIII) is submitted first to a catalytic radicalary cyclization, and then to an esterification reaction. Entecavir can be obtained by submitting compound (V) to a desilylation reaction to remove the TBS group and then to a Mitsunobu coupling with 2-amino-6-chloroguanine, followed by hydrolysis. It also relates to some new intermediates of the process.

Abstract: The invention relates to a process for preparing 1-aryl-pyrazol-3-one intermediates, tautomers, and salts thereof, to novel intermediates, and to the use of the intermediates in the preparation of sigma receptor inhibitors.

Abstract: Compositions and methods for the preparation of enantiomerically enriched .alpha.,.alpha.-disubstituted amino acid precursors are presented. Briefly, allylic electrophiles are alkylated with oxazolones in the presence of a base and catalytic quantities of a transition metal complex incorporating a chiral phosphine ligand to yield 4,4-disubstituted-5(4H)-oxazolones. These precursors may be subsequently transformed either synthetically or enzymatically to yield enantiomerically enriched .alpha.,.alpha.-disubstituted amino acids.