Abstract: Aminopeptidase inhibitory activity is exhibited by compounds having the formula ##STR1## wherein R.sub.1 is hydrogen, alkyl, carboxyalkyl, halo-substituted alkyl, hydroxyalkyl, aminoalkyl, mercaptoalkyl, alkylthioalkyl, (cycloalkyl)alkyl, (heteroaryl)alkyl, arylalkyl, carbamoylalkyl, guanidinylalkyl or heteroaryl; andR.sub.2 and R.sub.3 are each independently hydrogen, alkyl, cycloalkyl, hydroxyalkyl, aminoalkyl, aryl, arylalkyl, heteroaryl or heteroarylalkyl.

Abstract: Azo dyestuffs which contain at least one water-solubilizing group and have the formula ##STR1## wherein K stands for the radical of a coupling component,R.sub.1 stands for CN, COOX, CONXY or COZ,R.sub.2 stands for hydrogen, halogen, CN, alkyl or aryl,R.sub.3 stands for alkyl or aryl,X stands for H, alkyl, alkenyl, cycloalkyl, aryl or aralkyl andY stands for H or alkyl andZ stands for alkyl or aryl,are highly suitable for dyeing polyamide fibres. The resulting dyeings are distinguished by good all-round fastness properties.

Abstract: This invention relates to organic acid-substituted guanidine compounds. Also disclosed are methods for preparing the compounds, compositions containing them, and methods for their use as anthelmintics.

Abstract: There are disclosed compounds of Formulas I and II: ##STR1## wherein R.sup.1 and R.sup.2 may be hydrogen, lower alkyl having from 1 to 8 carbon atoms, lower alkenyl having from 3 to 6 carbon atoms, lower alkoxy having from 1 to 6 carbon atoms, hydroxy, nitro, amino, halo including chlorine, bromine, iodine, and fluorine, phenyl, alkanoyl having from 2 to 6 carbon atoms or they are bonded to one another to form a cycloalkene ring fused to the thiophene ring and having a total of from 5 to 7 annular ring carbon atoms, and R.sup.3 is an aliphatic or an aromatic group such as lower alkyl, e.g., methyl or ethyl. Such compounds are useful as intermediates in the production of tiprinast and related compounds.There is also disclosed a process for the regioselective synthesis of a compound of Formula I wherein R.sup.1 is CH.sub.3 and R.sup.2 is (CH.sub.3).sub.2 CHCH.sub.2 which comprises reacting a mixture of compounds of the following formulas: ##STR2## and ##STR3## with trichloroacetonitrile under acidic conditions.

Abstract: Thienopyridinone derivatives of the general formula: ##STR1## in which Y represents hydrogen or a lower alkyl group and X represents: a hydroxy, lower alkanoyloxy, lower alkoxy unsubstituted or substituted by a hydroxy, lower alkoxy, di-(lower alkyl)-amino, piperidino, pyrrolidino, morpholino or N-(lower alkyl)-piperazino group,a group of formula: ##STR2## in which R' and R", which are the same or different, each represent hydrogen or a lower alkyl, W represents hydrogen or a lower alkyl radical or a vinyl or ethynyl group and Z represents hydrogen or a lower alkyl radical,a phenyl radical unsubstituted or substituted by an atom of fluorine, chlorine, bromine or iodine or by a hydroxy, lower alkoxy or nitro group,a group of formula: ##STR3## in which Z has the same meaning as above, an amino, lower alkylamino or --NHCOOZ group in which Z has the same meaning as above and pharmaceutically acceptable salts thereof.They possess antibacterial properties.

Abstract: Processes for alkylating certain 3-oxo-4-substituted phenyl-5-amino-2,3-dihydrofurans and 2,3-dihydrothiophenes. The process effects replacement of the 5-amino group with a new amino group having the desired substitution. The products are useful as herbicides.

Abstract: 2,2-Dimethyl-3-arylcyclopropanecarboxylic acids and esters, suitable as insecticide intermediates, of the formula ##STR1## in which Ar is naphthyl or substituted furyl, thienyl or phenyl, andR.sup.1 is hydrogen or alkyl, are produced by subjecting ##STR2## to radical polymerization to produce ##STR3## reacting that with chlorine or bromine to produce ##STR4## and reacting that with an alkali metal or alkaline earth metal hydroxide or carbonate. Various intermediates II and III are new.

Abstract: Nitroaryl carbonyl Formula (IIA) compounds, their nitrodihydroaryl carbonyl Formula (I) intermediates, processes for preparing Formula (II) compounds, and a process for preparing Formula (I) compounds, wherein each process comprises the reaction of a nitroaryl compound with a silane.

Abstract: A process for the manufacture of the heterocyclic compounds of the formula: ##STR1## wherein R is hydrogen, lower alkyl or phenyl, which comprises simultaneously decarboxylating and dinitrating a compound of the formula: ##STR2## wherein R has the meaning stated above, and finally hydrolyzing off the acyl group.

Abstract: This invention relates to amine derivatives and salts thereof. These compounds have an anti-ulcer activity which is effective to human beings and animals. This disclosure relates to such compounds, a process for the preparation thereof and an anti-ulcer agent containing the same.

Abstract: This invention relates to a novel N-acyl acidic amino acid diamide derivative represented by the general formula or a salt thereof: ##STR1## wherein each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4, which may be the same or different, represents a hydrogen atom or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl or aralkyl group, or R.sup.1 and R.sup.2 and/or R.sup.3 and R.sup.4, when taken together with the respective adjacent nitrogen atoms, form a substituted or unsubstituted heterocyclic group; R.sup.5 represents a substituted or unsubstituted cycloalkyl, acyl or heterocyclic group; A represents a bond or a substituted or unsubstituted alkylene, alkenylene or alkadienylene group; and n is 1, 2 or 3. Said compound has an anti-ulcer activity which is effective to human beings and animals. This disclosure relates to such a compound, to a process for the production thereof and to an anti-ulcer agent containing the same.

Abstract: The novel compounds of this invention and their pharmaceutically acceptable salts exhibit cardioselective .beta.-adrenergic blocking activity, with a direct relaxing effect on the .beta..sub.2 -adrenergic receptors and are useful as antihypertensive, cardioprotective, antiarrhythmic and, antianginal agents.

Abstract: Novel compounds of the general formula ##STR1## wherein Ar represents a substituted or unsubstituted aromatic or heterocyclic group; W represents alkylene of from 1 to about 10 carbon atoms; and B represents --NR.sub.2 COR.sub.1, --NR.sub.2 CONR.sub.1 R.sub.3, --NR.sub.2 SO.sub.2 R.sub.1, --NR.sub.2 SO.sub.2 NR.sub.1 R.sub.3, or --NR.sub.2 COOR.sub.1 wherein R.sub.1, R.sub.2 and R.sub.3 may be the same or different and may be hydrogen, alkyl, alkoxyalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, or aralkyl, except that R.sub.1 is not hydrogen when B is --NR.sub.2 SO.sub.2 R.sub.1 or --NR.sub.2 COOR.sub.1, or R.sub.1 and R.sub.3 may together with N form a 5 to 7 momoered heterocyclic group; and the pharmaceutically acceptable salts thereof. These compounds exhibit .beta.-adrenergic blocking activity and are also useful in the treatment of glaucoma.

Abstract: Hydroxybenzylamino derivatives have been prepared from an appropriate hydroxybenzaldehyde and an amine followed by reduction. These compounds are found to be active topical anti-inflammatory agents.

Abstract: Compounds of the formula ##STR1## in which R.sup.1 is an optionally substituted aryl or heteroaryl radical,R.sup.2 is an alkyl or alkenyl radical which is optionally substituted by alkoxy or cycloalkyl, or an optionally substituted aryl or heteroaryl radical, and X is an optionally aklyl-substituted methylene radical or a direct bond, but if X is a direct bond R.sup.2 is not aryl,or physiologically acceptable acid addition salts thereof, exhibit activity on the circulation system particularly as hypotensive agents.

Abstract: Amidine compounds of the formula ##STR1## and pharmaceutically acceptable acid addition salts thereof are novel compounds and are useful as powerful anti-trypsin, anti-plasmin, anti-kallikrein and anti-thrombin agents. They are also useful as a powerful anti-complement agent.

Abstract: Unsymmetrical N-substituted bis-carbamoyl sulfide compounds exhibit exceptional broad spectrum pesticidal activity coupled with extremely low mammalian toxicity and phytotoxicity.

Abstract: A process is herein described for catalytically reducing nitroaromatic compounds by displacement of hydrogen from carbon monoxide and water or from synthesis gas to nitroaromatic compounds, the catalytic reduction being catalyzed by complexes of rhodium, iridium, ruthenium and osmium; said process is characterized in that the CO+H.sub.2 O system or the (CO+H.sub.2)+H.sub.2 O system is caused to react with a nitroaromatic compound of formula:Ar--(NO.sub.2).sub.x (I)wherein Ar is an aryl or hetero-aryl group, also substituted by inert groups; x is an integer from 1 to 3, in the presence of a complex catalyst of formula:[MChel(L).sub.2 ].sup.+ X.sup.- (II)or of a catalyst composed by carbonyl compounds and chelants of formula:Mz(CO).sub.y +nChel (III)wherein M=Rh, Ir, Ru, Os; "Chel" is a bidentate or tridentate aromatic nitrogen chelating compound; "L" is a molecule of carbon monoxide or of an olefin or half a molecule of a diolefin; X.sup.- is an anion selected from Cl.sup.-, Br.sup.-, I.sup.-, PF.sub.6.sup.

Abstract: This application relates to 4-amino-4,5-dihydro-2-thiophenecarboxylic acid, the C.sub.1-6 alkyl esters thereof and to their use in the treatment of epilepsy.

Abstract: Substituted carbamoyloximino-tetrahydrothiophenes or derivatives thereof of the formula ##STR1## in which R.sup.1 represents an alkyl, alkoxyalkyl, alkenyl or alkinyl group,R.sup.2 represents a hydrogen atom, an alkyl group or a group of the general formula --SR.sup.3 or --S.sub.2 R.sup.6, whereinR.sup.3 represents an alkyl, halogenoalkyl, optionally substituted phenyl, or alkoxycarbonyl group or a grouping of the general formula --NR.sup.4 R.sup.5, or a radical which is identical to the rest of the molecule to which the group --SR.sup.3 is bonded,R.sup.4 represents an alkyl, alkoxycarbonyl or optionally substituted phenylsulphonyl group,X represents a hydrogen or halogen atom or a grouping of the general formula --OR.sup.5 or --SR.sup.5,Y represents a halogen atom or a grouping of the general formula --OR.sup.5 or --SR.sup.5,R.sup.5 represents an alkyl group,R.sup.6 represents an alkyl group or an optionally substituted phenyl group, andn is 0, 1 or 2,which possess pesticidal activity.

Abstract: Symmetrical N-substituted bis-carbamoyl sulfide compounds exhibit exceptional broad spectrum pesticidal activity coupled with extremely low mammalian toxicity and phytotoxicity.

Abstract: The present invention provides a multistep process for the preparation of 2-(thien-2-yl)- and 2-(thien-3-yl)-ethylamine intermediates of the general formula:- ##STR1## in which R.sub.1, in the 2-, 3-, 4- or 5-position, is a hydrogen or halogen atom, a nitro, amino, cyano or carboxyl group, a linear or branched alkyl or alkoxy radical or a heterocyclic or non-heterocyclic aromatic radical, which is optionally mono- or polysubstituted, R.sub.2 is a hydrogen atom, a linear or branched alkyl radical or a heterocyclic or non-heterocyclic aromatic radical, which is optionally mono- or polysubstituted, and Ar is a heterocyclic or non-heterocyclic aromatic radical, which is optionally mono- or polysubstituted, when the aminoethyl radical is in the two position and the radical R.sub.1 is in the 4- or 5-position, the above intermediates can be converted into 4,5,6,7-tetrahydrothieno[3,2-c]pyridine derivatives according to a procedure set forth in U.S. Pat. No. 4,127,580.

Abstract: The present invention provides a process for the preparation of 2-(thien-2-yl)- and 2-(thien-3-yl)-ethylamine derivatives of the general formula: ##STR1## in which R.sub.1, in the 2-, 3-, 4- or 5-position, is a hydrogen or halogen atom, a nitro, carboxyl, cyano or amino group, a linear or branched alkyl or alkoxy radical or a heterocyclic or non-heterocyclic aromatic radical, which is optionally mono- or polysubstituted, the aminoethyl chain is in the 2- or 3-position, R.sub.2, R.sub.3 and R.sub.4, which are the same or different, are hydrogen atoms or heterocyclic or non-heterocyclic aromatic radicals, which are optionally mono- or polysubstituted, and Ar is a heterocyclic or non-heterocyclic aromatic radical, which is optionally mono- or polysubstituted.

Abstract: An N-sulphenylated oxime-carbamate of the formula ##STR1## in which R.sup.1 is optionally substituted alkyl, cycloalkyl, aryl or aralkyl,R.sup.2 is alkyl, alkenyl or alkynyl, orR.sup.1 and R.sup.2 together are an alkylene bridge having 1-6 C atoms, one of R.sup.3 and R.sup.4 is the radical ##STR2## and the other is alkyl, alkenyl, alkynyl, halogenoalkyl, halogenoalkenyl or alkoxyalkyl,R.sup.5 is alkyl,R.sup.6 is alkyl, halogenoalkyl, optionally substituted phenyl, alkoxycarbonyl or dialkylamino, NR.sup.8 --SO.sub.2 R.sup.7, or a radical identical to the radical to which the grouping --S--R.sup.6 is bonded,R.sup.7 is alkyl, dialkylamino or optionally substituted phenyl,R.sup.8 is alkyl, andX is O or S,which possesses pesticidal activity.

Abstract: Hydroxamic acid esters of the formula ##STR1## in which R.sup.1 is an optionally substituted alkyl, cycloalkyl, aryl or aralkyl radical andR.sup.2 is an alkyl, alkenyl or alkinyl radical, orR.sup.1 and R.sup.2 together are an alkylene bridge with 2 to 4 carbon atoms,one of the radicals R.sup.3 and R.sup.4 is ##STR2## while the other is an alkyl, alkenyl, alkinyl, halogenoalkenyl or alkoxyalkyl radical, andX is O or S,which possess pesticidal properties. Intermediates therefor wherein one of N--OR.sup.3 and N--OR.sup.4 is N--OH or a carbonyl group are also new.

Abstract: The present invention provides a process for the preparation of 2-(thienyl-2)- and 2-(thienyl-3)-ethylamines of the general formula: ##STR1## in which R.sub.1, which is in the 2-, 3-, 4- or 5-position, is a hydrogen atom, a straight-chained or branched alkyl radical or a heterocyclic or non-heterocyclic aromatic radical, which is optionally mono- or polysubstituted, or R.sub.1 is an alkoxy radical, a halogen atom or a nitro, carboxyl, cyano or amino group; the aminoethyl chain is in the 2- or 3-position of the thiophene nucleus; R.sub.2 is a hydrogen atom or a straight-chained or branched alkyl radical or a heterocyclic or non-heterocyclic aromatic radical, which is optionally mono- or poly-substituted; and Ar is a heterocyclic or non-heterocyclic aromatic radical, which is optionally mono- or poly-substituted.

Abstract: (1R,cis)-Oxyimino-substituted cyclopropanecarboxylic acids are prepared via a (1R,4R,5S)-2-acetoxy-6,6-dimethyl-4-oxo-3-oxabicyclo[3.1.0]hexane intermediate.

Abstract: Sulfides prepared by reacting a sulfoxide with a hydrazine or hydroxylamine derivative or a quaternary salt thereof are useful starting materials for the preparation of drugs, pesticides and dyes.

Abstract: Compounds of the formula: ##STR1## wherein R.sup.1 is H or alkyl; R.sup.2 and R.sup.3 are independently H, alkyl, aryl or substituted aryl; R.sup.4 is H or alkoxycarbonyl; R.sup.5 is H, acyl or a cation; and Z is thienyl or substituted thienyl.The compounds exhibit grass herbicide activity and are prepared via the reaction of the appropriately substituted cyclohexane-1,3-dione with the appropriate thienylmethoxyamine derivative and optionally acylating this product at the 3-hydroxy position or converting it to the cation salt.

Abstract: Bis(carboxamide) derivatives being useful as histamine H.sub.2 receptor antagonists or anti-peptic ulcer agents are provided from certain dicarboxylic acid derivatives.

Abstract: Novel oxime ethers and oxime esters of the formula I given herein have various advantageous effects with regard to stimulation of plant growth, particularly in the early stage of development of the plant. Furthermore, such compounds have the property of rendering, in the sense of an antidote action, agricultural chemicals which would otherwise damage the plants (phytotoxic chemicals) more compatible with the cultivated plants. Herbicides that are insufficiently selective can be used for example in the presence of such oxime derivatives in specific cultivated crops for combating weeds, without disadvantageous consequences for the cultivated plants.

Abstract: (1R,cis)-Oxyimino-substituted cyclopropanecarboxylic acids are prepared via a (1R,4R,5S)-4-acetoxy-6,6-dimethyl-2-oxo-3-oxabicyclo [3.1.0]hexane intermediate.

Abstract: Disclosed are azo compounds having the formula ##STR1## in which R.sup.4 is straight or branched lower alkylene, Z is 1-3 groups selected from such heteroatom groups as --OH, lower alkanoyloxy, lower alkoxy, lower alkoxycarbonyl, lower alkoxyalkoxy, mono- or dialkylamino, --CN, carbamoyl, formamide, lower alkyl substituted carbamoyl, lower alkoxycarbonylamino, lower alkanoylamino, hydroxy substituted lower alkoxy, halogen, lower alkylthio, lower alkylsulfonyl, and various heterocyclic groups such as furyl and pyrrolidono, R is selected from straight or branched lower alkyl, phenyl and phenyl substituted with straight or branched lower alkyl, halogen, or straight or branched lower alkoxy, R.sup.2 is hydrogen or lower alkyl, and A is an aniline, tetrahydroquinoline, or benzomorpholine coupler component which may be substituted with a wide variety of groups.

Abstract: Diphenylalkanoether and diphenylalkanone oxime-ether derivatives of the formula: ##STR1## wherein R.sup.1 and R.sup.2 are each independently an aryl group optionally substituted with 1 to 3 substituents selected from the group consisting of halogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, nitro, cyano, di(C.sub.1 -C.sub.4)alkylamino, amino, benzyloxy, hydroxyl, C.sub.1 -C.sub.4 alkylthio, C.sub.1 -C.sub.4 alkylsulfinyl, C.sub.1 -C.sub.4 alkylsulfonyl, C.sub.1 -C.sub.4 alkanoylamino, C.sub.1 -C.sub.4 alkylamino and N-(C.sub.1 -C.sub.4)alkyl-N-(C.sub.1 -C.sub.4)alkanoylamino, Z.sup.1 is a group of the formula: ##STR2## (wherein R.sup.3 and R.sup.4 are each independently a hydrogen atom, a C.sub.1 -C.sub.4 alkyl group or an ar(C.sub.1 -C.sub.

Abstract: This disclosure described novel (monosubstituted-amino)heteroaryl carboxylic acids and analogs which are useful as hypolipidemic and antiatherosclerotic agents.

Abstract: Antiallergically-active pyrimidine derivatives of the formula ##STR1## wherein R.sup.1 is hydrogen, chlorine, bromine or C.sub.1-4 -alkyl, and R.sup.2 is hydrogen or methyl, prepared starting from corresponding 4-oxothieno-[3,2-d]pyrimidine derivatives, are described.

Abstract: Compounds of the formula ##STR1## wherein R.sup.1 and R.sup.3 each is hydrogen or R.sup.1 and R.sup.3 together form a second carbon-to-nitrogen bond, R.sup.2 is hydrogen or cyano, R.sup.4 is alkyl and Ar is one of certain aromatic moieties.The compounds can be used as abscission agents for the loosening of fruit and/or leaves on plants.

Abstract: Disclosed are novel intermediates and their preparation, and the preparation therefrom of 2-halo-3-nitro-5-acyl thiophenes which themselves are important intermediates for the preparation of azo dyes of the type, ##STR1## wherein C.sup.1 represents typically any aniline, tetrahydroquinoline, benzomorpholine or the like coupler and the acyl group contains from 1-10 carbons. It has been found that if 2-acyl thiophene is treated with a hydroxylamine compound, e.g., a salt of hydroxylamine, including sulphate, chloride or the like, to form the oxime prior to the 2-position halogenation and 3-position nitration steps, various side reactions such as halogenation of the acyl group and nitration of the 5-position are avoided, the yield of each step is improved, and the reactions are less sensitive to the deleterious effects of temperature variations and excess reactants. The oxime derivative is readily reconverted to the acyl derivative after the halogenation and nitration steps have been completed.

Abstract: Novel thiophene compounds having utility as biotin intermediates and blood lipid lowering agents, as well as related processes and intermediates, are disclosed.

Abstract: Novel amino derivatives of 2-hydroxy-6,9-methano-11-amino-5,6,7,8,9,10-hexahydro-benzocyclooctenes, methods for their preparation, and their use as effective analgesic agents is described.

Abstract: Thiophene derivatives having utility as blood lipid lowering agents and as antiobesity agents are disclosed.

Abstract: Novel thiophene compounds having utility as biotin intermediates and blood lipid lowering agents, as well as related processes and intermediates, are disclosed.

Abstract: Compounds of the formula: ##STR1## are disclosed wherein R is C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 haloalkyl, C.sub.3 to C.sub.8 cycloalkyl, phenyl, halophenyl, naphthyl, benzyl, indanyl, phenacyl, p-nitrophenacyl, xylyl or acetoxymethyl; R.sup.1 is phenyl, benzyl or phenyl or benzyl substituted by halo, nitro, dialkylamino, alkoxy or trifluoromethyl, lower alkyl or allyl; and X is halo. The compounds are intermediates in the manufacture of penicillins.

Abstract: The invention concerns novel pesticidal esters of the pyrethrin or pyrethroid type in which the methylene group bonded to the ester carbonyl and/or ester oxygen bears a fluorine substituent. The compounds of the invention are active against insect pests including flies, moths, aphids and beetles and acarina pests including ticks.

Abstract: Phenylaminothiophenacetic acids of formula I ##STR1## wherein R.sup.1 denotes a hydrogen atom, a chlorine atom, a bromine atom or a methyl group,R.sup.2 denotes a --CH.sub.2 --COOH group or a --CH.sub.2 --COOR.sup.6 group,R.sup.3 denotes a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or a trifluoromethyl group,R.sup.4 has one of the meanings of R.sup.3,R.sup.5 denotes a hydrogen atom, a halogen atom or an alkyl group,R.sup.6 denotes an alkyl group (with from 1 to 5 carbon atoms), which is optionally substituted by hydroxyl, hydroxyalkoxy or alkanoyloxy groups, or a benzyl group andn denotes 1 or 2,and salts of the acids have outstanding antiphlogistic, analgesic and antipyretic activities.

Abstract: Novel guanylamidines and the pharmaceutically acceptable acid addition salts thereof having activity as hypoglycemic agents are disclosed.

Abstract: This disclosure describes anthracene-9,10-bis-carbonyl-hydrazones and derivatives thereof useful as antibacterial agents, for inhibiting the growth of transplanted mouse tumors, and for inducing the regression and/or palliation of leukemia and related cancers.

Abstract: Novel heterocyclic compounds shown by the formula ##STR1## wherein Het represents a 5-membered or 6-membered heterocyclic group which may have substituent(s); Z represents a sulfur atom or oxygen atom; X represents an oxygen atom or the unsubstituted or substituted imino group shown by N--R.sub.1 (wherein R.sub.

Abstract: A polymer having aromatic or heterocyclic rings as the only structural elements said aromatic or heterocyclic rings containing at least two nitro groups is disclosed as well as a method of preparing the same. The polymers are useful as binding agents for thermo stable propellants and can be easily formed into films. They remain thermally stable up to temperatures of at least 200.degree. C.

Abstract: The invention relates to a series of new compounds, salts thereof and to methods for the preparation of the compounds which have the general formula ##STR1## in which R.sub.1 stands for an unsubstituted or substituted phenoxy, phenylthio, benzyl, phenylsulfinyl, or anilino radical;R.sub.2 stands for a --YR.sub.2 ' radical, in which Y represents --O--, --S--, or --NH--, and R.sub.2 ' represents C.sub.1 -C.sub.6 -alkyl, C.sub.2 -C.sub.6 -alkenyl or -alkynyl; or methyl or ethyl substituted with phenyl, furyl, thienyl or pyridyl;R.sub.3 and R.sub.4 which can be the same or different, and unsubstituted or substituted, stand for hydrogen or for a straight or branched C.sub.1 -C.sub.8 -alkyl, C.sub.2 -C.sub.8 -alkenyl or -alkynyl radical, a C.sub.5 -C.sub.7 -cycloalkyl, a phenyl, or a 5-, 6- or 7-membered heterocyclic ring system containing not more than two hetero atoms selected from the group consisting of oxygen, sulphur and nitrogen, or for a C.sub.1 -C.sub.