Abstract: The invention discloses a novel intermediate for preparing tapentadol and analogues thereof, wherein the structural formula is shown as formula I or II, and the groups are defined as the specification. The invention further discloses a method for preparing the novel intermediate and use of the intermediate for preparing tapentadol and analogues thereof. The invention can remarkably improve the product yield and quality of tapentadol, reduce the production cost, and simplify the production procedure. The preparation process is environment friendly, thus more suitable for the requirements of industrial production.

Abstract: This invention pertains generally to prostacyclin analogs and methods for their use in promoting vasodilation, inhibiting platelet aggregation and thrombus formation, stimulating thrombolysis, inhibiting cell proliferation (including vascular remodeling), providing cytoprotection, preventing atherogenesis and inducing angiogenesis. Generally, the compounds and methods of the present invention increase the oral bioavailability and circulating concentrations of treprostinil when administered orally.

Abstract: The invention discloses a novel intermediate for preparing tapentadol and analogues thereof, wherein the structural formula is shown as formula I or II, and the groups are defined as the specification. The invention further discloses a method for preparing the novel intermediate and use of the intermediate for preparing tapentadol and analogues thereof. The invention can remarkably improve the product yield and quality of tapentadol, reduce the production cost, and simplify the production procedure. The preparation process is environment friendly, thus more suitable for the requirements of industrial production.

Abstract: To provide a novel compound having both a surface-activating ability and a polymerization controlling ability. A compound represented by the following general formula (1) or (2): wherein, R1 and R3 are an organic group having the hydrophile-lipophile balance (HLB) determined by Griffin's method of 3 or more. The definitions of R1, R2, R3, R4, Z, p and q are described in the Description.

Abstract: The present invention provides compounds that are effective in treating central nervous system disorders and maintaining normal brain function. Methods of making and using the compounds are also provided.

Abstract: A thiocarbonyl compound represented by the following formula (a) is useful as a RAFT agent. By using this, a process for producing a polymer having a excellent reactivity or monomer conversion rate and its polymer are provided.

Abstract: A thiocarbonylthio compound and free radical polymerization employing the same. The thiocarbonylthio compound is represented by formula (I) or (II): wherein Z can be independently perfluoroalkyl, alkyl, haloalkyl, aryl, alkylaryl, haloalkylaryl, arylalkyl, aminoalkyl, alkylamino, alkoxy, alkoxyaryl, alkylsulfonyl, alkylsulfonylaryl, dialkylphosphinyl, or dialkylphosphinothioyl; R1 and R2 can be each independently hydrogen, alkyl, aryl, alkylaryl, arylalkyl, aminoalkyl, alkylamino, alkoxy or alkoxyaryl; R3 is alkyl, aryl, aminoalkyl, alkylamino, alkoxy or alkoxyaryl. Furthermore, R3 can also be alkyl, aryl, alkylaryl, arylalkyl, aminoalkyl, alkylamino, alkoxy, haloalkylaryl, alkylsilyl, alkylthio, alkylthioaryl, or substituent containing CN, CO, COOH, COOCH3 or heterocyclic moieties; and R4 is perfluoroalkyl. The thiocarbonylthio compound can be used as a reversible chain transfer agent in a free radical polymerization to obtain a polymer with a controlled molecular weight and narrow polydispersity.

Abstract: The present invention relates to a process for the preparation of 1-(2-ethyl-butyl)-cyclohexanecarboxylic acid which is useful as an intermediate in the preparation of pharmaceutical active compounds.

Abstract: The invention provides a method for preparing an aqueous dispersion of polymer particles comprising the following steps: (i) preparing a dispersion having a continuous aqueous phase, a dispersed organic phase comprising one or more ethylenically unsaturated monomers, and an amphiphilic RAFT agent as a stabiliser for said organic phase, and (ii) polymerising said one or more ethylenically unsaturated monomers under the control of said amphiphilic RAFT agent to form said aqueous dispersion of polymer particles, novel amphiphilic RAFT agents for use in this method, novel RAFT agents useful in making these amphiphilic RAFT agents and methods for their manufacture.

Abstract: There is provided an organic sulfur compound having an excellent controlling effect on harmful arthropods which is represented by formula (I): wherein R1 represents a C3-C6 haloalkyl group having at least one fluorine atom and at least one atom selected from group consisting of a chlorine atom, a bromine atom and an iodine atom, R2 represents a cyano group and the like, R3 represents a hydrogen atom, a halogen atom or a C1-C4 alkyl group, R4 represents a C1-C5 fluoroalkyl group, and n represents 0, 1 or 2.

Abstract: This invention concerns a free radical polymerization process, selected chain transfer agents employed in the process and polymers made thereby, in which the process comprises preparing polymer of general Formula (A) and Formula (B) comprising contacting: (i) a monomer selected from the group consisting of vinyl monomers (of structure CH2?CUV), maleic anhydride, N-alkylmaleimide, N-arylmaleimide, dialkyl fumarate and cyclopolymerizable monomers; (ii) a thiocarbonylthio compound selected from Formula (C) and Formula (D) having a chain transfer constant greater than about 0.1; and (iii) free radicals produced from a free radical source; the polymer of Formula (A) being made by contacting (i), (ii) C and (iii) and that of Formula (B) by contacting (i), (ii) D, and (iii); and (iv) controlling the polydispersity of the polymer being formed by varying the ratio of the number of molecules of (ii) to the number of molecules of (iii); wherein Q, R, U, V, Z, Z?, m, p and q are as defined in the text.

Abstract: A thiocarbonylthio compound and free radical polymerization employing the same. The thiocarbonylthio compound is represented by formula (I) or (II): wherein Z can be independently perfluoroalkyl, alkyl, haloalkyl, aryl, alkylaryl, haloalkylaryl, arylalkyl, aminoalkyl, alkylamino, alkoxy, alkoxyaryl, alkylsulfonyl, alkylsulfonylaryl, dialkylphosphinyl, or dialkylphosphinothioyl; R1 and R2 can be each independently hydrogen, alkyl, aryl, alkylaryl, arylalkyl, aminoalkyl, alkylamino, alkoxy or alkoxyaryl; R3 is alkyl, aryl, aminoalkyl, alkylamino, alkoxy or alkoxyaryl. Furthermore, R can also be alkyl, aryl, alkylaryl, arylalkyl, aminoalkyl, alkylamino, alkoxy, haloalkylaryl, alkylsilyl, alkylthio, alkylthioaryl, or substituent contaning CN, CO, COOH, COOCH3 or heterocyclic moieties; and R4 is perfluoroalkyl. The thiocarbonylthio compound can be used as a reversible chain transfer agent in a free radical polymerization to obtain a polymer with a controlled molecular weight and narrow polydispersity.

Abstract: The invention provides a process for synthesising functionalised chain transfer polymers of Formula (1) or Formula (2) using thiocarbonyl thio compounds as chain transfer agents. Why R1 is a moiety comprising a functional group; Q is obtained from an olefinically unsaturated monomer; R? is selected from the group consisting of alkyl, substituted alkyl, alkoxy, substituted alkoxy, an aromatic saturated or unsaturated carbocyclic or heterocyclic ring, optionally substituted with one or more substituents, amino alkyl, cyanoalkyl, hydroxylalkyl, saturated and unsaturated amido; an organometallic species, a polymer chain and any of the foregoing substituted with one or more CN or OH groups; q=an integer of at least 2; p=an integer of at least 1. Chain transfer agents and polymers produced by the method are also provided.

Abstract: The present invention provides novel processes for the preparation of a cyclopentanone of Formula II and a lactone of Formula I, which are useful in the production of prostaglandins: wherein Z, R2, R3, X1, X2, and are as defined in the specification. The invention also provides novel enantiomerically enriched compounds.

Abstract: The present invention relates to a novel malononitrile compound represented by the formula (A): wherein, R1 represents C1 to C6 alkyl that may be substituted with halogen, C2 to C6 alkenyl that may be substituted with halogen, etc; R2 represents hydrogen atom or C1 to C6 alkyl that may be substituted with halogen; R3 represents hydrogen atom or C1 to C6 alkyl; R4 represents hydrogen atom or C1 to C6 alkyl; R5 represents C1 to C6 alkyl that may be substituted with halogen, C3 to C6 alkenyl that may be substituted with halogen, etc, or R4 and R5 may be combined at their terminal and represent ethylene that may be substituted with C1 to C3 alkyl or trimethylene that may be substituted with C1 to C3 alkyl; and Z1 and Z2, which are the same or different, represent oxygen atom or sulfur atom. The malononitrile compound has an efficient pesticidal activity and can control effectively pests such as insect pests, acarine pests, nematode pests and the like.

Abstract: This invention concerns a free radical polymerization process, selected chain transfer agents employed in the process and polymers made thereby, in which the process comprises preparing polymer of general Formula (A) and Formula (B) comprising contacting: (i) a monomer selected from the group consisting of vinyl monomers (of structure CH2?CUV), maleic anhydride, N-alkylmaleimide, N-arylmaleimide, dialkyl fumarate and cyclopolymerizable monomers; (ii) a thiocarbonylthio compound selected from Formula (C) and Formula (D) having a chain transfer constant greater than about 0.1; and (iii) free radicals produced from a free radical source; the polymer of Formula (A) being made by contacting (i), (ii) C and (iii) and that of Formula (B) by contacting (i), (ii) D, and (iii); and (iv) controlling the polydispersity of the polymer being formed by varying the ratio of the number of molecules of (ii) to the number of molecules of (iii); wherein Q, R, U, V, Z, Z?, m, p and q are as defined in the text.

Abstract: The present invention relates to low odor ?-cyano-dithiocarboxylic ester compounds of formula I for use as chain transfer agents in free radical polymerizations, and polymerization processes employing them: wherein R1 is selected from alkyl, substituted alkyl, heteroaryl, substituted heteroaryl, alkylaryl, substituted alkylaryl, aryl, substituted aryl, alkoxy, aryloxy, thioalkyl, thioaryl, substituted thioalkyl, substituted thioaryl, secondary amino and tertiary amino; R2 is selected from alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, and COOR3; and R3 is alkyl.

Abstract: Polymers and copolymers synthesized by means that yield a narrow range of molecular weights can have different properties than polymers synthesized by conventional means. In order to obtain such polymers, however, polymerization must be controlled. One type of controlled polymerization is the reversible addition-fragmentation chain transfer (RAFT) process, which has characteristics of a living polymerization. The present invention discloses a group of dithioesters and trithioesters suitable as chain transfer agents for RAFT polymerization. The present invention also discloses RAFT polymerizations conducted in aqueous media.

Abstract: The present invention relates to a process for preparing dithioesters in which a dithiocarboxylic acid and/or a dithiocarboxylic salt is reacted with a vinyl compound and/or an alkyl compound which includes a leaving group, the reaction being carried out in a biphasic system in which one of the phases comprises water and the weight ratio of the aqueous phase to the organic phase lies in the range from 95:5 to 5:95.

Abstract: The invention relates to the use of 2-(3,4-dihydroxyphenyl)ethyl-substituted carbonic acid derivatives as antioxidants or free-radical scavengers, in particular to the use for protecting human cells and tissues from the harmful, aging-accelerating effects of free-radicals and reactive oxygen compounds.

Abstract: The present invention provides an industrial method for recovering and purifying 2-acetylthio-3-phenylpropionic acid, particularly an optically active

Abstract: Compounds of the formula: in which n, q, A, X, G, Y, Z, R, R2, R3, R4, R5, R7 and R9 are as defined in claim 1, and, where appropriate, E/Z isomers, E/Z isomer mixtures and/or tautomers thereof, in each case in the free form or in an agrochemically suitable salt form, can be used as agrochemical active compounds and can be prepared in a manner known per se.

Abstract: Compounds of the formula I 1

Abstract: The present invention relates to methods for the synthesis of chiral non-racemic products, e.g., enantiomerically-enriched hemiesters, from prochiral starting materials, e.g., meso anhydrides. The present invention also relates to catalysts for the aforementioned methods, and methods for synthesizing these catalysts.

Abstract: Method of separating molecules by providing a cross-linked polymer gel having a cross-linking moiety of the formula 1

Abstract: New phenolic compounds of formula (I) 1

Abstract: The present invention is directed to novel propoxyphene derivatives which are synthesized for the covalent attachment to antigens (proteins or polypeptides) for the preparation of antibodies or receptors to propoxyphene and propoxyphene metabolites. The resulting novel antigens may be used for the production of antibodies or receptors using standard methods. Once generated, the antibodies or receptors and the novel derivatives which are covalently attached to proteins, polypeptides or labels may be used in the immunoassay process.

Abstract: Compounds of the formula ##STR1## in which n, q, A, X, G, Y, Z, R, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.7 and R.sub.9 are as defined in claim 1, and, where appropriate, E/Z isomers, E/Z isomer mixtures and/or tautomers thereof, in each case in the free form or in an agrochemically suitable salt form, can be used as agrochemical active compounds and can be prepared in a manner known per se.

Abstract: The present invention is directed to double prodrugs containing polymeric-based transport forms. These polymeric prodrugs are preferably of the formula: ##STR1## wherein: B is a leaving group or a residue of an amine-containing target moiety;G is ##STR2## or CH.sub.2 ; Y.sub.1-2 are independently O or S;M is X or Q; where X is an electron withdrawing group and Q is a moiety containing a free electron pair positioned three to six atoms from C(.dbd.Y.sub.2);R.sub.1, R.sub.4, R.sub.7, R.sub.8, R.sub.9, R.sub.10 and R.sub.13 are independently selected from the group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.3-12 branched alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted alkyls, C.sub.3-8 substituted cycloalkyls, aryls, substituted aryls, aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6 heteroalkyls;R.sub.2, R.sub.3, R.sub.5 and R.sub.6 are independently selected from the group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.1-6 alkoxy, phenoxy, C.sub.1-8 heteroalkyls, C.sub.

Abstract: Dithiocarboxylates, and in particular, dithiocarbamates, block the induced expression of the endothelial cell surface adhesion molecule VCAM-1, and are therefor useful in the treatment of cardiovascular disease, including atherosclerosis, post-angioplasty restenosis, coronary artery diseases, and angina, as well as noncardiovascular inflammatory diseases that are mediated by VCAM-1.

Abstract: A method for the treatment of cardiovascular diseases and noncardiovascular inflammatory diseases that are mediated by VCAM-1 is provided that includes the removal, decrease in the concentration of, or prevention of the formation of oxidized polyunsaturated fatty acids, or interferes with a complex formed between a polyunsaturated fatty acid or an oxidized polyunsaturated fatty acid and a protein or peptide that mediates the expression of VCAM-1. A method is also provided for suppressing the expression of a redox-sensitive gene or activating a gene that is suppressed through a redox-sensitive pathway, that includes administering an effective amount of a substance that prevents the oxidation of the oxidized signal, and typically, the oxidation of a polyunsaturated fatty acid, or interferes with a complex formed between the oxidized signal and a protein or peptide that mediates the expression of the redox gene.

Abstract: Dithiocarboxylates, and in particular, dithiocarbamates, block the induced expression of the endothelial cell surface adhesion molecule VCAM-1, and are therefor useful in the treatment of cardiovascular disease, including atherosclerosis, post-angioplasty restenosis, coronary artery diseases, and angina, as well as noncardiovascular inflammatory diseases that are mediated by VCAM-1.

Abstract: Dithiocarboxylates, and in particular, dithiocarbamates, block the induced expression of the endothelial cell surface adhesion molecule VCAM-1, and are therefor useful in the treatment of cardiovascular disease, including atherosclerosis, post-angioplasty restenosis, coronary artery diseases, and angina, as well as noncardiovascular inflammatory diseases that are mediated by VCAM-1.

Abstract: A method for the treatment of cardiovascular diseases and noncardiovascular inflammatory diseases that are mediated by VCAM-1 is provided that includes the removal, decrease in the concentration of, or prevention of the formation of oxidized polyunsaturated fatty acids, or interferes with a complex formed between a polyunsaturated fatty acid or an oxidized polyunsaturated fatty acid and a protein or peptide that mediates the expression of VCAM-1. A method is also provided for suppressing the expression of a redox-sensitive gene or activating a gene that is suppressed through a redox-sensitive pathway, that includes administering an effective amount of a substance that prevents the oxidation of the oxidized signal, and typically, the oxidation of a polyunsaturated fatty acid, or interferes with a complex formed between the oxidized signal and a protein or peptide that mediates the expression of the redox gene.

Abstract: A method for the treatment of cardiovascular diseases and noncardiovascular inflammatory diseases that are mediated by VCAM-1 is provided that includes the removal, decrease in the concentration of, or prevention of the formation of oxidized polyunsaturated fatty acids, or interferes with a complex formed between a polyunsaturated fatty acid or an oxidized polyunsaturated fatty acid and a protein or peptide that mediates the expression of VCAM-1. A method is also provided for suppressing the expression of a redox-sensitive gene or activating a gene that is suppressed through a redox-sensitive pathway, that includes administering an effective amount of a substance that prevents the oxidation of the oxidized signal, and typically, the oxidation of a polyunsaturated fatty acid, or interferes with a complex formed between the oxidized signal and a protein or peptide that mediates the expression of the redox gene.

Abstract: Compounds of the formula I ##STR1## and disulfides thereof and salts thereof are important intermediate products for the preparation of compounds having a microbicidal and plant-immunizing action, of the formula III ##STR2## In the compounds of the formulae I and III: X is halogen,n is 0,1,2 or 3;Z is CN, CO-A or CS-A,A is hydrogen, halogen, OR.sub.1, SR.sub.2 and N(R.sub.3)R.sub.4 ;R.sub.1 to R .sub.4 are hydrogen, a substituted or unsubstituted, open-chain, saturated or unsaturated hydrocarbon radical containing not more than 8 carbon atoms, a substituted or unsubstituted cyclic, saturated or unsaturated hydrocarbon radical containing not more than 10 carbon atoms, substituted or unsubstituted benzyl or phenethyl, a substituted or unsubstituted alkanoyl group containing not more than 8 carbon atoms, a substituted or unsubstituted benzoyl group or a substituted or unsubstituted heterocyclyl radical; or R.sub.3 and R.sub.

Abstract: A method for the treatment of cardiovascular diseases and noncardiovascular inflammatory diseases that are mediated by VCAM-1 is provided that includes the removal, decrease in the concentration of, or prevention of the formation of oxidized polyunsaturated fatty acids, or interferes with a complex formed between a polyunsaturated fatty acid or an oxidized polyunsaturated fatty acid and a protein or peptide that mediates the expression of VCAM-1. A method is also provided for suppressing the expression of a redox-sensitive gene or activating a gene that is suppressed through a redox-sensitive pathway, that includes administering an effective amount of a substance that prevents the oxidation of the oxidized signal, and typically, the oxidation of a polyunsaturated fatty acid, or interferes with a complex formed between the oxidized signal and a protein or peptide that mediates the expression of the redox gene.

Abstract: Organic compounds having at least one ethylenically-unsaturated group are described, the organic compounds being suitable for use in coatable compositions as reactive diluents; compounds of the invention preferably have a divalent organic linking moiety devoid of reactive groups other than optional ethylenically-unsaturated groups, and a polar organic moiety and are particularly adept in solubilizing aminoplast resins having radiation-curable pendant groups.

Abstract: Fluorinated alkene compounds useful for and methods of controlling nematodes, insects, and acarids that prey on agricultural crops, these compounds having the structure: ##STR1## where Q is --(C.dbd.S)--R.sub.1 and R.sub.1 is --OR.sub.5, --SR.sub.5, halogen, --NHOH or --NR.sub.5 R.sub.6. Each of R.sub.5 and R.sub.6 is independently hydrogen; an aliphatic or an aromatic group; a C.sub.1 -C.sub.12 aliphatic amine group; a C.sub.2 -C.sub.12 aliphatic carboxylic acid group; or R.sub.5 and R.sub.6 when taken together with the N of R.sub.1 are a protein amino acid or a cyclic group. Polar compounds are particularly useful for systemic control of pests.

Abstract: A method for the topical or systemic treatment of disorders mediated by proteases which result in skin or mucosal lesions, and in particular, pemphigus, cicatricial pemphigoid, bullous pemphigoid, lichen planus, and canker sores, is disclosed wherein the host is treated with an effective amount of N-acetyl ysteine or a derivative thereof, or its pharmaceutically acceptable salt, optionally in a pharmaceutically acceptable diluent or carrier for systemic or topical delivery.

Abstract: Di(aromatic) compounds corresponding to the following formula: ##STR1## in which: Ar represents either ##STR2## X represents a divalent radical, Z represents O, S or a divalent radical,and R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 represent a hydrogen atom or various organic radicals, and the salts of the compounds of formula (I) when R.sub.1 is a carboxylic acid function.Use in human and veterinary medicine and in cosmetics.

Abstract: Organic compounds having at least one ethylenically-unsaturated group are described, the organic compounds being suitable for use in coatable compositions as reactive diluents; compounds of the invention preferably have a divalent organic linking moiety devoid of reactive groups other than optional ethylenically-unsaturated groups, and a polar organic moiety and are particularly adept in solubilizing aminoplast resins having radiation-curable pendant groups.

Abstract: Dye-donor element for use according to thermal dye sublimation transfer comprising a support having thereon a dye layer containing a dye corresponding to the following formula ##STR1## wherein Z represents CN, COOR.sup.1 or CONR.sup.2 R.sup.3 ;R.sup.1, R.sup.2 and R.sup.3 each independently represent hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, or R.sup.2 and R.sup.3 together represent the necessary atoms to close a heterocyclic nucleus or substituted heterocyclic nucleus;Y represents OR.sup.4 or NR.sup.5 R.sup.6 or CN;R.sup.4 represents hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, SO.sub.2 R.sup.7, COR.sup.7, CSR.sup.7, POR.sup.7 R.sup.8 ;R.sup.5 and R.sup.6 each independently has one of the significances given to R.sup.4 or represent substituted or unsubstituted amino, or R.sup.5 and R.sup.

Abstract: The compounds of the formula (I) ##STR1## in which R.sup.1 -R.sup.4, W, X, Y and Z are as defined in claim 1 are suitable for controlling harmful plants in crops.

Abstract: Di(aromatic) compounds corresponding to the following formula: ##STR1## in which: Ar represents either ##STR2## n=1 or 2 or: ##STR3## X represents a divalent radical, Z represents O, S or a divalent radical, and R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 represent a hydrogen atom or various organic radicals, and the salts of the compounds of formula (I) when R.sub.1 is a carboxylic acid function. Use is in human and veterinary medicine and in cosmetics.

Abstract: A group of 2-amino-3-aroyl-benzo[.beta.]thiophenes are prepared by preparing an .alpha.-hydroxy thioacetamide by silyl mediated condensation of an aldehyde with an anion of dialkylamino thioformamide, cyclizing the .alpha.-hydroxy thioamide, and subsequently acylating the benzo[.beta.]thiophene to yield the 2-amino-3-aryl derivative. These compounds may be treated with suitable phenyl Grignard reagents, and after deprotection, yield 6-hydroxy-2-(4-hydroxyphenyl)-3-[4-(2-piperidinoethoxy)benzoyl]benzo[.beta .]thiophene.

Abstract: Compounds of the formula I ##STR1## where n, W, X, Y, Z, R.sup.1, R.sup.2, and R.sup.3 are as defined herein exhibit fungicidal, insecticidal, and acaracidal activity.

Abstract: Polysulfide derivatives, having the general formula (A--S--S--).sub.2 X--S--S--A processes for their production and their use for crosslinking of reversion-stable rubber vulcanizates are provided. Crosslinking with reduced reversion and loss of elastomeric properties with age is achieved by the crosslinking system provided by the invention.

Abstract: The preparation of magnesium benzyl fluoromalonate and other equivalent materials, the synthetic equivalents of the --CH.sub.2 F moiety, is described. Reaction between these reagents and the in situ-formed imidazolides of various carboxylic acids gives beta-keto-alpha-fluoroesters, which upon hydrogenation and spontaneous decarboxylation yields fluoromethyl ketones in excellent yields. The overall transformation from RCOOH to RCOCH.sub.2 F is thus illustrated.

Abstract: Compounds of general formula I: ##STR1## wherein: R.sup.1 represents a C.sub.1 -C.sub.6 alkyl, phenyl, thiophenyl, substituted phenyl, phenyl(C.sub.1 -C.sub.6)alkyl, heterocyclyl, (C.sub.1 -C.sub.6)alkylcarbonyl phenacyl or substituted phenacyl group; or, when n=O, R.sup.1 represents SR.sup.x, wherein R.sup.x represents a group: ##STR2## R.sup.2 represents a hydrogen atom or a C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkenyl, phenyl(C.sub.1 -C.sub.6)alkyl, cycloalkyl(C.sub.1 -C.sub.6)alkyl or cycloalkenyl(C.sub.1 -C.sub.6)alkyl group;R.sup.3 represents an amino acid residue with R or S stereochemistry or a C.sub.1 -C.sub.6 alkyl, benzyl, (C.sub.1 -C.sub.6 alkoxy)benzyl or benzyloxy(C.sub.1 -C.sub.6 alkyl) group;R.sup.4 represents a hydrogen atom or a C.sub.1 -C.sub.6 alkyl group;R.sup.5 represents a hydrogen atom or a methyl group;n is an integer having the value 0, 1 or 2; andA represents a C.sub.1 -C.sub.6 hydrocarbon chain, optionaly substituted with one or more C.sub.1 -C.sub.