Abstract: A method of synthesis of a partially retro-inverso peptide incorporating at least one malonyl residue of formula (III) ##STR1## wherein R represents the side chain of an .alpha.-amino acid, is described which is characterized in that said malonyl residue is incorporated by condensing a 5-substituted-2,2-dimethyl-1,3-dioxane-4,6-dione of formula (IV) ##STR2## wherein R' is the side-chain R wherein the functional groups, if any, are suitably protected, with an amino acid, amino acid amide, peptide fragment, or pseudo-peptide fragment wherein the terminal carboxyl group, if present, and the possible side-chain functionalities are suitably protected and the reactive amino group is tri-alkyl-silylated.The new compounds of formula (VI) and a process for the preparation of a partially retro-inverso tuftsin analog which involves use of said method and said intermediate are also described and claimed.

Abstract: A method of synthesis of a partially retro-inverso peptide incorporating at least one malonyl residue of formula (III) ##STR1## wherein R represents the side chain of an .alpha.-amino acid, is described which is characterized in that said malonyl residue is incorporated by condensing a 5-substituted-2,2-dimethyl-1,3-dioxane-4,6-dione of formula (VI) ##STR2## wherein R' is the side-chain R wherein the functional groups, if any, are suitably protected, with an amino acid, amino acid amide, peptide fragment, or pseudo-peptide fagment wherein the terminal carboxyl group, if present, and the possible side-chain functionalities are suitably protected and the reactive amino group is tri-alkyl-silylated.The new compounds of formula (VI) and a process for the preparation of a partially retro-inverso tuftsin analog which involves use of said method and said intermediate are also described and claimed.

Abstract: The process of the invention is useful for the preparation of L-.alpha.-aminoacids and is based on the use of an N-carbamyl-.alpha.-aminoacid compound which is contacted with a E.C.3.5.2.2, a dihydropyrimidine hydrolase, enzyme to form a D-hydantoin. The D-hydantoin is hydrolyzed and racemized to form the D-N-carbamyl-.alpha.-aminoacid and the L-N-carbonyl-.alpha.-aminoacid. The L-N-carbamyl-.alpha.-aminoacid is thereafter transformed into the corresponding L-.alpha.-aminoacid.

Abstract: This invention relates to a process for the preparation of D(-) mandelic acid by the acid hydrolysis of the corresponding carbamate in an aqueous environment at a temperature of between 40.degree. and 100.degree. C. and at a pH of between 1 and 3.5.The invention also relates to a process for the enzymatic hydrolysis of racemic 5-substituted 2,4-oxazolidinediones to give only one of the two possible optical isomers, i.e., the D-carbamyl-.alpha.-hydroxy acid. The free D-.alpha.-hydroxy acid can be obtained from the optically active carbamyl derivative by simple hydrolysis. Of particular interest is the case in which the D-.alpha.-hydroxy acid is D(-)mandelic acid. The enzymatic activity required for preparing the carbamyl derivative of D(-)mandelic acid has been found both in homogenised veal liver and in a series of microorganisms, including Agrobacterium radiobacter, Bacillus brevis, Bacillus stearothermophilus, Pseudomonas sp., Pseudomonas desmolytica, Pseudomonas fluorescens, Pseudomonas putida.

Abstract: This invention relates to a process for preparing carbamyl derivatives of .alpha.-hydroxy acids by the hydrolysis of 5-substituted 2,4-oxazolidinediones.The carbamyl derivatives can be further hydrolyzed to .alpha.-hydroxy acids.The invention also relates to a process for the enzymatic hydrolysis of racemic 5-substituted 2,4-oxazolidinediones to give only one of the two possible optical isomers, i.e. the D-carbamyl-.alpha.-hydroxy acid. The free D-.alpha.-hydroxy acid can be obtained from the optically active carbamyl derivative by simple hydrolysis. Of particular interest is the case in which the D-.alpha.-hydroxy acid is D(-)mandelic acid. The enzymatic activity required for preparing the carbamyl derivative of D(-)mandelic acid has been found both in homogenized veal liver and in a series of microorganisms, including Agrobacterium radiobacter, Bacillus brevis, Bacillus stearothermophilus, Pseudomonas sp., Pseudomonas desmolytica, Pseudomonas fluorescens, Pseudomonas putida.

Abstract: In the preparation of 4-chloro-2-methyl-crotonaldehyde, an important starting material for the preparation of the acetate of Vitamin A, the improvement consisting in that isoprene monoepoxide (1:2-epoxy-2-methyl-3-butene) is chlorinated either with tert.butyl hypochlorite in the vapor phase, or with cupric chloride in the liquid phase. The reaction is preferably carried out in an inert siliceous or aluminous substrate at temperatures ranging from 60.degree. C to 150.degree. C. Lithium chloride has proven to be useful as a catalyst, but by no means essential.