Abstract: An object of the present invention is to provide a method for producing a propionic acid derivative with high productivity. The object can be achieved by a method for producing a compound represented by formula (1): wherein R1 is a halogen atom or the like, R2 and R3 are each independently a hydrogen atom, a halogen atom, or an organic group, X is an oxygen atom or a sulfur atom, R4 and R5 are each independently a hydrogen atom, a halogen atom, or a hydrocarbon group optionally having one or more substituents, R6 is a hydrocarbon group optionally having one or more substituents; the method comprising step A of reacting a compound represented by formula (2): with a compound represented by formula (3): M(R1)n, wherein M is a cation, n is an integer corresponding to the valence of M, and a compound represented by formula (4): R6—X—H; and step B of separating, by filtration, the compound represented by formula (5): MFn from the mixture obtained by the above reaction.

Abstract: To provide a fluorinated compound having an RF group with at most 6 carbon atoms, whereby a fluorinated polymer having a highly durable water/oil repellency can be produced, and an environmental load is little, and a fluorinated polymer and a fluorinated copolymer having a highly durable water/oil repellency and presenting little environmental load, obtainable by polymerizing such a fluorinated compound. A fluorinated compound represented by the following formula (I) and its polymer: CH2?C(M)COO(CH2)nPhCOO(CH2)mCrF2r+1??(I) (in the formula (I), M is a hydrogen atom, a methyl group or a halogen atom, n is an integer of from 0 to 2, Ph is a phenylene group, m is an integer of from 1 to 4, and r is an integer of from 1 to 6).

Abstract: The present invention relates to polymeric derivatives, which can be conjugated to an amino-containing drug to improve its in vivo properties. The polymeric derivative can subsequently be released to yield the drug in its native form. Methods of preparing and using these polymeric derivatives and drug conjugates are described.

Abstract: To provide a fluorinated compound having an RF group with at most 6 carbon atoms, whereby a fluorinated polymer having a highly durable water/oil repellency can be produced, and an environmental load is little, and a fluorinated polymer having a highly durable water/oil repellency and presenting little environmental load, obtainable by polymerizing such a fluorinated compound. A fluorinated compound represented by the following formula (I) and its polymer: CH2?C(M)COO(CH2)nPhXPhZCrF2r+1??(I) (in the formula (I), M is a hydrogen atom, a methyl group or a halogen atom, n is an integer of from 0 to 2, Ph is a phenylene group, X is CH2O or OCH2, Z is a single bond, a C1-4 alkylene group containing an etheric oxygen atom, or COO(CH2)m (wherein m is an integer of from 1 to 4), and r is an integer of from 1 to 6).

Abstract: The present invention relates to methods for synthesizing compounds of formula I or pharmaceutically acceptable salts thereof: I wherein each of X, Alk1, Alk2, and W are as defined and described herein.

Abstract: Absorbable polyurethanes, polyamides and polyester urethanes prepared from at least one compound selected from: or the diamines and diisocyanates thereof, wherein each X represents a member independently selected from —CH2COO— (glycolic acid moiety), —CH(CH3)COO— (lactic acid moiety), —CH2CH2OCH2COO— (dioxanone), —CH2CH2CH2CH2CH2COO— (caprolactone moiety), —(CH2)yCOO— where y is one of the numbers 2, 3, 4 or 6-24 inclusive, and —(CH2CH2O)z?CH2COO— where z? is an integer between 2 and 24, inclusive; each Y represents a member independently selected from —COCH2O— (glycolic ester moiety), —COCH(CH3)O— (lactic ester moiety), —COCH2OCH2CH2O— (dioxanone ester), —COCH2CH2CH2CH2CH2O— (caprolactone ester), —CO(CH2)mO— where m is an integer between 2, 3, 4 or 6-24 inclusive, —COCH2O(CH2CH2O)n— where n is an integer between 2 and 24, inclusive; R? is hydrogen, benzyl or an alkyl group, the alkyl group being either straight-chained or branched; p is an integer between 1 and 4, inclusive; and Rn represents one or more

Abstract: A compound of the formula wherein R1 and R1? are the same, and wherein R1 and R1? are each aromatic groups; and wherein R2 and R2? and R3 each, independently of the others, are alkylene groups, arylene groups, arylalkylene groups, or alkylarylene groups; or wherein, in embodiments, R1 and R1? can be the same or different, and wherein R1 and R1? each, independently of the other is an alkyl group having a least one ethylenic unsaturation, an arylalkyl group having at least one ethylenic unsaturation, an alkylaryl group having at least one ethylenic unsaturation, or an aromatic group, provided that at least one of R1 and R1? is an aromatic group; and provided that neither of R1 or R1? is a photoinitiator group.

Abstract: A process for preparing monocarboxylic perfluoropolyethers of formula: A-O—(RF)z—(CFY)t—C(O)OX (I) wherein: X is H, C1-C10 alkyl, or an aryl group; Y=F, CF3; t=1, 2 or 3; A is a C1-C4 perfluoroalkyl end group; z=0 or 1; RF is a perfluorooxyalkylene chain; having a number average molecular weight in the range 180-8,000; comprising the following steps: a) one or more distillations of perfluoropolyethers (PFPE) of formula T-O—(RF)z-T? (II) wherein: z and RF are as above defined; T, T?, equal to or different from each other, are selected from acyl fluoride or carbonyl-containing functional end groups and non functional end groups to obtain one PFPE fraction of formula (II) wherein the difference between the minimum and the maximum molecular weight of the components is lower than or equal to 600; b) partial fluorination of the fraction obtained in a); c) esterification c1) and/or hydrolysis c2) of the mixture obtained in b); d) distillation of the product obtained in c2) or in c1).

Abstract: Absorbable polyurethanes, polyamides and polyester urethanes prepared from at least one compound selected from: or the diamines and diisocyanates thereof, wherein each X represents a member independently selected from —CH2COO— (glycolic acid moiety), —CH(CH3)COO— (lactic acid moiety), —CH2CH2OCH2COO— (dioxanone), —CH2CH2CH2CH2CH2COO— (caprolactone moiety), —(CH2)yCOO— where y is one of the numbers 2, 3, 4 or 6-24 inclusive, and —(CH2CH2O)z?CH2COO— where z? is an integer between 2 and 24, inclusive; each Y represents a member independently selected from —COCH2O— (glycolic ester moiety), —COCH(CH3)O— (lactic ester moiety), —COCH2OCH2CH2O— (dioxanone ester), —COCH2CH2CH2CH2CH2O— (caprolactone ester), —CO(CH2)mO— where m is an integer between 2, 3, 4 or 6-24 inclusive, —COCH2O(CH2CH2O)n— where n is an integer between 2 and 24, inclusive; R? is hydrogen, benzyl or an alkyl group, the alkyl group being either straight-chained or branched; p is an integer between 1 and 4, inclusive; and Rn represents one or more

Abstract: The present invention provides a process for producing highly pure fluoro-compounds by making use of N-(2-chloro-1,1,2-trifluoroethyl)diethylamine. The process produces little or no chlorinated by-products.

Abstract: There are provided a compound represented by a general formula (b1-1) shown below suitable as an acid generator for a resist composition, a compound represented by a general formula (I) shown below suitable as a precursor for the compound represented by the general formula (b1-1), an acid generator, a resist composition, and a method of forming a resist pattern. [Chemical Formula 1] X-Q1-Y1—SO3?M+??(I) X-Q1-Y1—SO3?A+??(b1-1) (wherein, Q1 represents a bivalent linking group or a single bond; Y1 represents an alkylene group which may contain a substituent group or a fluorinated alkylene group which may contain a substituent group; X represents an aromatic cyclic group of 5 to 30 carbon atoms which contains a fluorine atom and may contain a substituent group; M+ represents an alkali metal ion; and A+ represents an organic cation.

Abstract: A process for preparing an oligomeric phenolic detergent composition comprising contacting an oil soluble alkylphenol with an alkaline earth metal base, an alpha amino acid, and a C1 to C6 aldehyde, in the in the presence of a C2 to C6 alkylene glycol and a C2 to C4 carboxylic acid; and reacting under reactive conditions at a temperature of from 150° C. to 225° C. The oligomeric phenolic detergent product can be employed in a lubricating oil.

Abstract: A method is described for the preparation of polymorphic forms of water-soluble derivatives of probucol compounds having the following formula where R1, R2, R3, R4, R5, R6, Z and Z? are defined herein.

Abstract: A method of synthesizing highly optically enriched &agr;-halo-esters comprises reacting acid halides with a cinchona alkaloid catalyst and a base to form intermediate ketenes. The ketenes are reacted with electrophilic halogenating reagents to produce &agr;-halo-esters with high enantiomeric excess. The base can be an inorganic salt. The thus-formed &agr;-halo-esters have utility in synthesizing other optically-pure materials.

Abstract: The invention relates to a process for the preparation of acyloxybenzenesulfonates starting from carbonyl halides and salts of phenolsulfonic acid which have a low water content. Surprisingly, it was discovered that acyloxybenzenesulfonates can be prepared in high yields and good grades, irrespective of the grade or reactivity of the phenolsulfonic acid derivative, if the reaction of the phenolsulfonic acid with an alkanecarboxylic acid derivative is carried out in an aliphatic or aromatic solvent in the presence of 0.5 to 25% by weight of a polyglycol ether.

Abstract: The present invention provides a process for transesterification of ketoester using polyaniline salt as catalyst, said process comprising reacting a keto ester with an alcohol in presence of a catalyst at a temperature range of 50 to 120° C. for a period in the range of 4 to 24 hours and separating the esters from the reaction mixture.

Abstract: New types of hydroxamic acid-based bifunctional chelators are provided. These chelators are designed to chelate metal ions that can be detected either by their paramagnetic or radioactive properties. Conjugation with peptides or protein can be achieved by the presence of a linker moiety in the molecular structure of these chelators.

Abstract: A process for preparing 2-hydroxycarboxylic esters having a quaternary &bgr;-carbon atom by reaction of glycidyl esters with an organoaluminum reagent is described.

Abstract: A description is given of a process for preparing dihydroxycarboxylic esters and of an overall process for preparing R-(+)-&agr;-lipoic acid.

Abstract: The invention relates to novel optically active polymerizable dipeptides, to the process for the preparation thereof, to the polymerization thereof and to the use of the polymers as adsorbents for the chromatographic separation of enantiomers.

Abstract: aPL analogs that (a) bind specifically to B cells to which an aPL epitope binds and are disclosed. Optimized analogs lack T cell epitope(s) are useful as conjugates for treating aPL antibody-mediated diseases. Conjugates comprising aPL analogs and nonimmunogenic valency platform molecules are provides as are novel nonimmunogenic valency platform molecules and linkers. Methods of preparing and identifying said analogs, methods of treatment using said analogs, methods and compositions for preparing conjugates of said analogs and diagnostic immunoassays for aPL antibodies are disclosed.

Abstract: Triazine, benzotriazole and benzophenone derivatives which are substituted or bridged with polyoxyalkylene groups, according to claim 1, and their use as UV absorbers, especially in photographic materials, in inks, including inkjet inks and printing inks, in transfer prints, in paints and varnishes, organic polymeric materials, plastics, rubber, glass, packaging materials, in sunscreens of cosmetic preparations and in skin protection compositions.

Abstract: Enantiomerically pure &bgr;-hydroxy esters are prepared by a process in which &bgr;-keto esters are reacted with hydrogen in the presence of catalysts of the formula LRuX2 where X is halogen, acetate, allyl, methallyl, 2-phenylallyl, perchlorate, trifluoroacetate, tetrafluoroborate, hexafluoroantimonate, hexafluorophosphate, hexafluoroarsenate or trichloroacetate, L is a bidentate phospholane of the formula I  where B=a bridging link with 1-5 carbon atoms between the two phosphorus atoms, R1=H, C1-C6-alkyl, aryl, alkylaryl or SiR23, R2=alkyl or aryl, m=0 or 1, R3=H or OR4, and R4=R1, with the proviso that if m=1 then R3=H and if m=0 then R3 ≠ H.

Abstract: The present invention provides a compound of the formula wherein when X is S; R is selected from the group consisting of CH3, CH2CH3, CH2Ph, (CH2)2Ph, (CH2)2CH3, (CH2)3CH3, (CH2)4CH3, CH2)5CH3, (CH2)6CH3, (CH2)2O(CH2)3CH3, CH2HC═CH(CH2)3CH3, CH2C≡C(CH2)3CH3, CH2C≡C(CH2)2CH3, CH2C≡CCH2CH3, CH2C≡CCH3, CH2C≡CH, CH2C≡C(CH2)4CH3, CH2C≡C(CH2)5CH3, CH2C≡C(CH2)6CH3, (CH2)2C≡C(CH2)2CH3, CH(Ch3)C≡C(CH2)3CH3, (CH2)6I, (CH2)6Br, (CH2)5Br, (CH2)5COOH and (CH2)5OCOCH3, and R′ is selected from the group consisting of CH3, CF3, CH2Cl, CH2Br, CH2CH3, NH2, and OSO2CH3; wherein when R is CH3, R′ can not be CH3 or CH2Cl; wherein when R is CH2CH3, R′ can not be CH3; wherein when X is Se, R is (CH2)6CH3, and R′ is CH3 or a pharmaceutically acceptable salt or hydrate thereof; and wherein when X is O, R is CH2C≡C(CH2)3CH3, and R′ is CH3 or a pharmaceutically acceptable salt or hydrate thereof.

Abstract: The invention relates to polymethacrylate acid-polyalkylene oxide block copolymers, to a process for their preparation and to their use as dispersants or suspension stabilizers for pigments and fillers, e.g. for metal oxides in ceramic materials, for pigments in inks used in ink jet printing and for fillers in thermosplastic and thermoset polymers.

Abstract: The invention relates to a process for the preparation of compounds of the general formula I in which R1 and R2 are identical or different and are a C1-C20-alkyl group, C3-C12-cycloalkyl group, C7-C12-aralkyl group or a mono- or binuclear aryl group, in which a ketone of the formula III or IV in which R1 and R2 have the above meaning, is asymmetrically hydrogenated.

Abstract: The present invention relates to a compound of the formula wherein R.sup.1 and R.sup.2 are selected from lower alkyl groups having 1-6 carbon atoms, substituted or unsubstituted aryl groups, and unsaturated alkyl groups having 1-6 carbon atoms; R.sup.3 is a substituted or unsubstituted lower alkyl group having 1-6 carbons; and R.sup.4 is selected from substituted or unsubstituted lower alkyl groups having 1-6 carbon atoms, substituted or unsubstituted aryl groups, and unsaturated alkyl groups having 1-6 carbon atoms. The present invention also relates to a pharmaceutical composition comprising the above compound, as well as a method of treating tumor cells with the compound.

Abstract: The present invention relates to the synthesis of a hydrazone .beta.-keto ester by the reaction of an alkyl diazoester with a hydrazone aldehyde in the presence of a Lewis acid In a preferred embodiment, the hydrazone .beta.-keto ester is then converted into a pyridazinone compound by the reaction with an alkyl acid chloride in the presence of a base, followed by acidification. A process for the production of a hydrazone aldehyde, which comprises contacting a hydrazine and glyoxal, is also described.

Abstract: The invention relates to a process for the preparation of compounds of the general formula I ##STR1## in which R.sup.1 and R.sup.2 are identical or different and are a C.sub.1 -C.sub.20 -alkyl group, C.sub.3 -C.sub.12 -cycloalkyl group, C.sub.7 -C.sub.12 -aralkyl group or a mono- or binuclear aryl group, in which a ketone of the formula III or IV ##STR2## in which R.sup.1 and R.sup.2 have the above meaning, is asymmetrically hydrogenated.

Abstract: The present invention provides novel compounds of the formula I and II for the treatment of non-insulin dependent diabetes mellitius (NIDDM) and a new use of known compounds for this purpose.

Abstract: A method of inhibiting bacterial sialidase comprising administering to a subject an inhibiting effective amount of a compound of formula I: ##STR1## wherein A is CO.sub.2 H, PO.sub.2 H, or SO.sub.2 H; B is N; R.sub.1 and R.sub.2 are H; R.sub.3 and R.sub.4 are, independently, H, OH, NO.sub.2, guanidino, or alkyl or alkenyl of from 1 to 3 carbons where the alkyl or alkenyl is unsubstituted or is substituted, independently, with one or more of OH, NH2, or halide; R.sub.5 is H; and R.sub.6 is COCH.sub.3, or COCI.sub.3 ; or an analog, pharmaceutically acceptable salt, derivative, or mixture thereof. A method of preventing a bacterial or trypanosomal infection using the compounds of formula I. A method of treating a bacterial or trypanosomal infection using the compounds of formula I. A pharmaceutical composition comprising a pharmaceutically acceptable carrier admixed with an inhibiting effective amount of a compound of formula I.

Abstract: The invention concerns activated amphetamine derivatives, a process for their production as well as their use for producing immunogens or detection conjugates carrying amphetamine groups. A further subject matter of the invention are new conjugates carrying amphetamine groups, a process for the production thereof as well as their use for the production of antibodies or for the determination of amphetamine or derivatives thereof.

Abstract: The present invention provides a compound of the formula ##STR1## wherein R is selected from the group consisting of CH.sub.3, CH.sub.2 CH.sub.3, (CH.sub.2).sub.2 CH.sub.3, (CH.sub.2).sub.3 CH.sub.3, (CH.sub.2).sub.4 CH.sub.3, (CH.sub.2).sub.5 CH.sub.3, (CH.sub.2).sub.6 CH.sub.3, (CH.sub.2).sub.2 O(CH.sub.2).sub.3 CH.sub.3, CH.sub.2 HC.dbd.CH(CH.sub.2).sub.3 CH.sub.3, CH.sub.2 C.tbd.C(CH.sub.2).sub.3 CH.sub.3, CH.sub.2 C.tbd.C(CH.sub.2).sub.2 CH.sub.3, CH.sub.2 C.tbd.CCH.sub.2 CH.sub.3, CH.sub.2 C.tbd.CCH.sub.3 and CH.sub.2 C.tbd.CH; and R' is selected from the group consisting of CH.sub.3, CF.sub.3, CH.sub.2 Cl and CH.sub.2 Br or a pharmaceutically acceptable salt or hydrate thereof. Also provided is a method of inhibiting the synthesis of prostaglandin endoperoxide syntase-2 (PGHS-2) in a mammal.

Abstract: The invention relates to a process for the preparation of aminomalonic acid esters and optionally their salts by the catalytic hydrogenation of a substituted malonic acid ester in an inert solvent, and optionally by the addition of an acid to the hydrogenation mixture. The process comprises carrying out the hydrogenation in the presence of a solid dehydrating agent and a solvent or solvent mixture in which the aminomalonic acid ester salt is substantially insoluble.

Abstract: A process for preparing polymeric amides is disclosed. The process comprises sequentially reacting a hydrocarbon polymer functionalized (e.g., via the Koch reaction) to contain acid, ester, thioacid and/or thioester groups with a heavy polyamine to form a partially derivatized product in which at least about 85% of the functional groups are converted to heavy (thio)amide groups, and then reacting the partially derivatized product with an excess of light amine to complete the derivatization by converting substantially all of the remaining functional groups to light (thio)amide groups. Products of the foregoing process are also disclosed, which products are useful as additives in fuels and in lubricants.

Abstract: A process for the preparation of compounds of the formula (1) in which R.sup.1, R.sup.2 and R.sup.3 are as defined in the specification, which includes reacting alcohols or carboxylic acids of the formula (2) in which R.sup.1, R.sup.2 and R.sup.3 are as defined in the specification, with a fluorinating agent of the formula (3) as defined in the specification.

Abstract: An acetamide derivative having the general formula (I): ##STR1## or a pharmacologically acceptable salt thereof; a synthetic intermediate of the above-mentioned acetamide derivative; a treating agent for peptic ulcer and for gastritis which comprises the above-mentioned compound having the general formula (I) as an effective ingredient, and a process for treating peptic ulcer and gastritis using the above-mentioned compound having the general formula (I), are disclosed.

Abstract: Protein, ligand and anti-ligand conjugated chelated metal radionuclides are provided for use in vivo. Intermediates are provided for preparing the compositions efficiently.

Abstract: An economical process for producing .alpha.-L-aspartyldipeptide amide derivatives useful as sweeteners, by using amino protecting groups which can be removed by hydrolysis under acidic conditions, resulting in conversion of a .beta.-carboxyl acid ester to a carboxylic acid.

Abstract: A process comprises contacting, in the presence of a catalyst, hydrogen sulfide or a mercaptan such as, for example, n-dodecyl mercaptan with an .alpha.,.beta.-unsaturated carbonyl or .alpha.,.beta.-unsaturated cyano compound such as, for example, methyl acrylate wherein the catalyst comprises a pyridine derivative such as, for example, 4-(dimethylamino)pyridine or an ion exchange resin such as, for example, "AMBERLYST A-21" to produce a 3-hydrocarbylthio derivative of the .alpha.,.beta.-unsaturated carbonyl or .alpha.,.beta.-unsaturated cyano compound such as, for example, methyl 3-(dodecylthio)propionate.

Abstract: Improved automatic dishwashing detergent compositions, especially granular detergents, comprising bleach activators which form multiperacids, especially specific monoquaternary substituted bis(peroxycarbonic) acids, upon perhydrolysis are provided.

Abstract: A di- or tri-ester polyether unsaturated acid amine reaction product effective as a fuel additive for reducing intake valve deposits and octane requirement increase, as well as controlling combustion chamber deposits, in gasoline engines is disclosed together with fuel compositions and methods of making and using the same. Also disclosed are compositions and methods for dispersing deposits in lubricating oil products.

Abstract: Improved detergent compositions, especially granular detergents, comprising bleach activators which form multiperacids, especially specific monoquaternary substituted bis(peroxycarbonic) acids, upon perhydrolysis are provided.

Abstract: A one pot process for the perfluoroalkylation and/or perfluoroacyloxylation of organic substrates is provided. The process comprises contacting a substrate with a perfluoroalkanoic anhydride in the presence of an inorganic peroxygen compound at a temperature of greater than 10.degree. C. Substrates that can be perfluoroalkylated and/or perfluoroacyloxylated include alkylbenzenes, halogenated aromatic compounds, alkoxybenzenes, aryl benzenes, and aromatic and aliphatic disulphides. Preferably, the perfluoroalkanoic anhydride is trifluoroacetic anhydride and the inorganic peroxygen compound is sodium percarbonate.

Abstract: Diisocyanates containing carboxylic acid ester groups corresponding to the formula: ##STR1## in which R and R.sup.1 represent specified groups are produced by phosgenation of the corresponding diamines, optionally present in the form of an ammonium salt. These diisocyanates are useful as starting materials in the production of plastics containing urethane and/or urea groups and as starting materials for the production of intermediate products used for the production of such plastics.

Abstract: Improved automatic dishwashing detergent compositions, especially granular detergents, comprising bleach activators which form multiperacids, especially specific monoquaternary substituted bis(peroxycarbonic) acids, upon perhydrolysis are provided.

Abstract: Improved detergent compositions, especially granular detergents, comprising bleach activators which form multiperacids, especially specific monoquaternary substituted bis(peroxycarbonic) acids, upon perhydrolysis are provided.

Abstract: (6S)-6,8-Dihydroxyoctanoic esters I ##STR1## (R.sup.1 =alkyl, cycloalkyl, aralkyl or aryl), are prepared by reducing a (3S)-3-hydroxyoctanedioic diester II ##STR2## (R.sup.2 =an R.sup.1 radical group) with a complex hydride and are mainly used as intermediates for synthesizing compounds of the type of liponic acid.

Abstract: .beta.-Carboxy sulfonyl compounds of the formula ##STR1## wherein R.sub.1 is aryl, R.sub.3 is hydrogen or alkyl, R.sub.3 and R.sub.4 are hydrogen or alkyl, Y is --O--, --S--, or --NR.sub.2 --, and R.sub.5 is alkyl or aryl are potent inhibitors of the enzyme acyl CoA:cholesterol acyltransferase (ACAT) and are thus useful for treating hypercholesterolemia and atherosclerosis.

Abstract: Therapeutic compounds have the formula:(X)j-(non-cyclic core moiety),j being an integer from one to three, the core moiety is non-cyclic and X is a racemic mixture, R or S enantiomer, solvate, hydrate, or salt of: ##STR1## *C is a chiral carbon atom, n is an integer from one to four (preferably from one to three), one or more carbon atoms of (CH.sub.2).sub.n may be substituted by a keto or hydroxy group, and m is an integer from one to fourteen. Independently, R.sub.1 and R.sub.2 may be a hydrogen, a straight or branched chain alkane or alkene of up to twelve carbon atoms in length, or --(CH.sub.2).sub.w R.sub.5, w being an integer from two to fourteen and R.sub.5 being a mono-, di- or tri-substituted or unsubstituted aryl group, substituents on R.sub.5 being hydroxy, chloro, fluoro, bromo, or C.sub.1-6 alkoxy. Or jointly, R.sub.1 and R.sub.2 form a substituted or unsubstituted, saturated or unsaturated heterocyclic group having from four to eight carbon atoms, N being a hetero atom. R.sub.