Abstract: A process for preparing 7-benzylpurine derivatives is provided. An acetylpurine nucleoside is reacted with a benzyl halide to benzylate the 7-position of the purine base, and an acid is then added to the reaction mixture to hydrolyze the glycoside bond. The 7-benzylpurines may be used to prepare 9-substituted purine derivatives.

Abstract: Purine derivatives in which a desired substituent is introduced into the 9-position only are synthesized by first introducing an easily-removable substituent in the 7-position of a purine base of natural purine nucleosides obtained through fermentation or derivatives thereof, then hydrolyzing the ribose moiety to form purine derivatives having the substituent in the 7-position, subsequently introducing the desired substituent in the 9-position, and then removing the substituent in the 7-position.

Abstract: A process for producing a 2-aralkyl-3-hydroxypropionic acid (or its ester), comprising the steps of: reacting a 3-hydroxy-2-methylene-3-arylpropionic acid ester, easily obtained by the reaction of an arylaldehyde with an acrylic acid ester, with an acid anhydride to form a 2-aralkylidene-3-acyloxypropionic acid ester; subjecting the same to hydrolysis or alcoholysis; and reducing the resulting 2-aralkylidene-3-hydroxypropionic acid or its ester. The reduction step may be conducted in the presence of a base.

Abstract: The present invention provides a simple and inexpensive method for producing &agr;-hydroxy-&bgr;-aminocarboxylic acids and their esters. An ester of an N-protected &agr;-amino acid ester is converted into a &bgr;-ketosulfoxide, which is then processed with an acid to give an &agr;-ketohemimercaptal. Next, this is acylated and then processed with a base to obtain an N-protected &agr;-acyloxy-&bgr;-amino-thioester, which is then saponified to obtain an intended compound. According to the method of the present invention, it is possible to produce &agr;-hydroxy-&bgr;-aminocarboxylic acid derivatives, which are intermediates in producing various HIV protease inhibitors, renin inhibitors and carcinostatics, from a-amino acids. The method comprises reduced reaction steps, the selectivity in the method to give the intended product is high, and the yield of the product obtained is high.

Abstract: A process for preparing 2,6-diaminopurine-2′-deoxyriboside and 2′-deoxyguanosine. These compounds may be used as materials for pharmaceuticals, such as antiviral agents and the like, and particularly as starting materials for antisense oligonucleotides.

Abstract: The present invention provides a simple and inexpensive method for producing &agr;-hydroxy-&bgr;-aminocarboxylic acids and their esters. An ester of an N-protected &agr;-amino acid ester is converted into a &bgr;-ketosulfoxide, which is then processed with an acid to give an &agr;-ketohemimercaptal. Next, this is acylated and then processed with a base to obtain an N-protected &agr;-acyloxy-&bgr;-amino-thioester, which is then saponified to obtain an intended compound. According to the method of the present invention, it is possible to produce &agr;-hydroxy-&bgr;-aminocarboxylic acid derivatives, which are intermediates in producing various HIV protease inhibitors, renin inhibitors and carcinostatics, from a-amino acids. The method comprises reduced reaction steps, the selectivity in the method to give the intended product is high, and the yield of the product obtained is high.

Abstract: A process for preparing optically active 2-hydroxymethyl-3-phenylpropionic acid by resolving (RS)-2-hydroxymethyl-3-phenylpropionic acid via crystallization of an optically active amine salt, where the amine is optically active cis-1-amino-2-indanol salt, optically active .alpha.-methylbenzylamine salt, or optically active 3-methyl-2-phenyl-1-butylamine salt.

Abstract: Novel intermediates of nucleoside derivatives, of which the 6-position of the nucleic acid base moiety is substituted with a halogen atom, are produced. Using those novel intermediates, even substrates, of which the 3'-position of the saccharide moiety is deoxylated, can be substituted at the 2'-position at an extremely high yield. Specifically, by subjecting a 3'-deoxy derivative of inosine to 6-halogenation to give a 6-halide of the derivative, and then subjecting it to 2'-deoxylation/substitution with a fluorine atom or the like, followed by further subjecting it to substitution with an amino group, a hydroxyl group or any other intended substituent at the 6-positioned halogen atom, nucleoside derivatives are produced at a high yield.Methods for producing nucleoside derivatives including 9-(2,3-dideoxy-2-fluoro-.beta.

Abstract: 9-Substituted purine derivatives of formula (4) ##STR1## are prepared by debenzylating a compound of formula (3): ##STR2##

Abstract: Provided is an industrially useful process for producing an optically active 2-hydroxy-4-arylbutyric acid or its ester. An optically active acyloxysuccinic anhydride is reacted with an aromatic compound in the presence of a Lewis acid to produce an optically active 2-acyloxy-4-oxo-4-arylbutyric acid. The 2-acyloxy-4-oxo-4-arylbutyric acid is converted to an optically active 2-acyloxy-4-arylbutyric acid through catalytic reduction. The 2-acyloxy-4-arylbutyric acid is hydrolyzed in the presence of an acid or an alkali to produce an optically active 2-hydroxy-4-arylbutyric acid. The 2-hydroxy-4-arylbutyric acid is reacted with an alcohol in the presence of an acid to produce an optically active 2-hydroxy-4-arylbutyric acid ester.

Abstract: Optically active N-(S-2-acetylthiomethyl-1-oxo-3-phenylpropyl)-glycine benzyl ester useful as an enkephalin inhibitory agent or ACE inhibitory agent can be produced at low cost in an industrial manner, by a method comprising subjecting optically active 2-hydroxymethyl-3-phenylpropionic acid and glycine benzyl ester to condensation to subsequently convert the hydroxyl group into an elimination group, and substituting the elimination group with an acetylthio group.

Abstract: A compound selected from the group consisting of(a) optically active 2-hydroxymethyl-3-phenylpropionic acid cis-1-amino-2-indanol salt,(b) optically active 2-hydroxymethyl-3-phenylpropionic acid .alpha.-methylbenzylamine salt,(c) optically active 2-hydroxymethyl-3-phenylpropionic acid 3-methyl-2-phenyl-1-butylamine salt,(d) a salt of (S)-2-hydroxymethyl-3-phenylpropionic acid with (1R, 2S)-(+)-cis-1-amino-2-indanol,(e) a salt of (R)-2-hydroxymethyl-3-phenylpropionic acid with (1S, 2R)-(-)-cis-1-amino-2-indanol,(f) a salt of (R)-2-hydroxymethyl-3-phenylpropionic acid with (S)-(-)-.alpha.-methylbenzylamine,(g) a salt of (S)-2-hydroxymethyl-3-phenylpropionic acid with (R)-(+)-.alpha.-methylbenzylamine,(h) a salt of (S)-2-hydroxymethyl-3-phenylpropionic acid with (S)-(-)-3-methyl-2-phenyl-1-butylamine, and(i) a salt of (R)-2-hydroxymethyl-3-phenylpropionic acid with (R)-(+)-3-methyl-2-phenyl-1-butylamine.

Abstract: The present invention provides a process for producing decahydro(4as, 8aS)isoquinoline-3(S)-carboxamides which are useful as intermediates of Saquinavir (EP 432694). Saquinavir is an anti-AIDS agent. The comprises reacting tetrahydroisoquinoline-3(S)-carboxylic acid with at least one of phosgene, phosgene dimer and triphosgene to form N-carboxy anhydride (NCA), then reacting NCA with an amine to produce a tetrahydroisoquinoline-3(S)-carboxamide derivative, and further reducing this derivative in the presence of a metal catalyst.

Abstract: Provided is an industrially useful process for producing an optically active 2-hydroxy-4-arylbutyric acid or its ester. An optically active acyloxysuccinic anhydride is reacted with an aromatic compound in the presence of a Lewis acid to produce an optically active 2-acyloxy-4-oxo-4-arylbutyric acid. The 2-acyloxy-4-oxo-4-arylbutyric acid is converted to an optically active 2-acyloxy-4-arylbutyric acid through catalytic reduction. The 2-acyloxy-4-arylbutyric acid is hydrolyzed in the presence of an acid or an alkali to produce an optically active 2-hydroxy-4-arylbutyric acid. The 2-hydroxy-4-arylbutyric acid is reacted with an alcohol in the presence of an acid to produce an optically active 2-hydroxy-4-arylbutyric acid ester.

Abstract: A process for preparing 7-benzylpurine derivatives is provided. An acetylpurine nucleoside is reacted with a benzyl halide to benzylate the 7-position of the purine base, and an acid is then added to the reaction mixture to hydrolyze the glycoside bond. The 7-benzylpurines may be used to prepare 9-substituted purine derivatives.

Abstract: Compounds formed by reacting a protected amino acid with an alkali metal enolate of an alkyl acetate are reacted with a halogenating agent for halogenation of the 2-position, or a protected amino acid is reacted with an alkali metal enolate of an alkyl halogenoacetate, to form a 4-amino-3-oxo-2-halogenobutanoic acid ester derivative, and hydrolysis and decarboxylation are conducted to produce a 3-amino-2-oxo-1-halogenopropane derivative or its salt. The present method is a useful process for producing a 3-amino-2-oxo-1-halogenopropane derivatives which can easily be converted to a 3-amino-1,2-epoxypropane.

Abstract: The present invention provides a simple and inexpensive method for producing .alpha.-hydroxy-.beta.-aminocarboxylic acids and their esters.An ester of an N-protected .alpha.-amino acid ester is converted into a .beta.-ketosulfoxide, which is then processed with an acid to give an .alpha.-ketohemimercaptal. Next, this is acylated and then processed with a base to obtain an N-protected .alpha.-acyloxy-.beta.-amino-thioester, which is then saponified to obtain an intended compound. According to the method of the present invention, it is possible to produce .alpha.-hydroxy-.beta.-aminocarboxylic acid derivatives, which are intermediates in producing various HIV protease inhibitors, renin inhibitors and carcinostatics, from a-amino acids. The method comprises reduced reaction steps, the selectivity in the method to give the intended product is high, and the yield of the product obtained is high.

Abstract: Purine derivatives in which a desired substituent is introduced into the 9-position only are synthesized by first introducing an easily-removable substituent in the 7-position of a purine base of natural purine nucleosides obtained through fermentation or derivatives thereof, then hydrolyzing the ribose moiety to form purine derivatives having the substituent in the 7-position, subsequently introducing the desired substituent in the 9-position, and then removing the substituent in the 7-position.

Abstract: The present invention provides a simple and inexpensive method for producing a-hydroxy-.beta.-aminocarboxylic acids and their esters. An ester of an N-protected .alpha.-amino acid ester is converted into a .beta.-ketosulfoxide, which is then processed with an acid to give an .alpha.-ketohemimercaptal. Next, this is acylated and then processed with a base to obtain an N-protected .alpha.-acyloxy-.beta.-amino-thioester, which is then saponified to obtain an intended compound. According to the method of the present invention, it is possible to produce .alpha.-hydroxy-.beta.-aminocarboxylic acid derivatives, which are intermediates in producing various HIV protease inhibitors, renin inhibitors and carcinostatics, from a-amino acids. The method comprises reduced reaction steps, the selectivity in the method to give the intended product is high, and the yield of the product obtained is high.

Abstract: Herein is disclosed a novel and industrially advantageous process for synthesizing acyclic nucleosides such as acyclovir and ganciclovir from ribonucleosides, which process comprises adding an acid catalyst and an acid anhydride to a solution of a ribonucleoside such as guanosine and an ester derivative of an acyclic sugar, and heating the mixture, whereby a transglycosilation reaction takes place between the ribose moiety of the ribonucleoside and the ester derivative of the acyclic sugar.Herein is also disclosed an industrially favorable method for the separation of 9-substituted purine nucleosides which are important intermediates for the synthesis of acyclic nucleosides such as acyclovir, ganciclovir, and the like from ribonucleosides, which method comprises crystallizing only the 9-isomer from a solution or suspension containing both a 9-substituted purine nucleoside and a 7-substituted purine nucleoside by cooling the solution or/and by adding a crystallizing solvent thereto.