Abstract: A method for the production of aliphatic fluoroformates, wherein carbonyl fluoride is made to react with aliphatic alcohol in the presence of sodium fluoride in ether at a temperature of ?20° to 50° C. The method is carried out using carbonyl fluoride obtained by reacting phosgene with surplus powdered sodium fluoride, whereby the grains thereof have a specific surface of 0.1 m2/g or more and/or an average diameter of 20 ?m or less, at a temperature ranging from 25° to 120° C. The method enables unstable fluoroformates such as tertiobutyl to be obtained with excellent yields.

Abstract: A process for producing N-formylleucine includes reacting leucine with formamide, precipitating the N-formylleucine, once the reaction is complete, at a temperature of approximately 0° to 40° C., by mixing the reaction medium with water and an acid, so that the final pH of the mixture is approximately 2 to 3, wherein the amount of water used in between approximately 1.5 and 5 parts per part by weight of starting formamide.

Abstract: The invention relates to a new process for the synthesis of a disubstituted carbodiimide, including a first stage of phosgenation of an N,N'-disubstituted urea in an organic solvent medium.After this first stage ammonia is added to the reaction mixture without preliminary isolation of any intermediate compound.The process is simple, relatively inexpensive and the yield is high.Disubstituted carbodiimides are organic synthesis intermediates used especially in pharmaceutical chemistry as coupling agents in peptide synthesis.

Abstract: The invention relates to a new process for the preparation of 1-bromoalkyl hydrocarbyl carbonates.The carbonates according to the invention are prepared by reacting an alpha-chlorinated carbonate of formula ##STR1## with an anhydrous brominated compound of formula ZBr in which Z represents hydrogen, the group (CH.sub.3).sub.3 -Si-, the group ##STR2## or bromine if R.sub.2 is other than an aromatic radical, in the presence of a catalyst chosen from the group consisting of heteroaromatic amines, quaternary ammonium or phosphonium halides, hexasubstituted guanidinium halides, alkaline earth metal halides or alkali metal halides in combination with a complexing agent for their cation.The carbonates according to the invention find their preferential applications as blocking agents for some antibiotics or as agents for the synthesis of phosphorus-containing carbonates which can be used as insecticides.

Abstract: The invention relates to carbonates of formula: ##STR1## in which X is a fluorine, chlorine or bromine atom and R.sup.1 is different from the ##STR2## group and represents: a substituted or non-substituted, saturated or unsaturated, aliphatic, araliphatic, primary, secondary, tertiary or cycloaliphatic radical. These .alpha.-chlorinated carbonates are prepared by the action of a compound of formula R.sup.1 OH on a chloroformate of formula: ##STR3## in a solvent medium in the presence of an acid scavenger which is added after the two preceding compounds. They are used to block the amine function of amino acids. The .alpha.-chlorinated carbonate and amino acid are reacted in a solvent medium at a temperature of -5.degree. to 100.degree. C. in the presence of an acid scavenger. Blocked amines are very useful in peptide synthesis.

Abstract: The invention relates to a new process for preparing active esters or carboyxlic acids, which consists in reacting a carboxylic acid, in the presence of an agent for binding hydrohalic acid, with a carbonate of formula: ##STR1## in which R.sup.1 denotes either a radical of formula ##STR2## in which R.sup.3 and R.sup.4, which may be identical or different, are not hydrogen atoms and denote organic radicals which may be substituted or unsubstituted and saturated or unsaturated, and may or may not be bound to a polymer, and which can be joined together to form a hetero-cyclic system with the nitrogen, atom,or a substituted or unsubstituted aryl radical which may or may not be bound to a polymer,R.sup.2 denotes a hydrogen atom, an aliphatic or cycloaliphatic radical which may be substituted or unsubstituted and saturated or unsaturated, or a substituted or unsubstituted aromatic radical,and X denotes a halogen atom.This process is especially useful for the synthesis of active esters of N-protected amino acids.

Abstract: The invention relates to a new process for preparing active esters or carboxylic acids, which consists in reacting a carboxylic acid, in the presence of an agent for binding hydrohalic acid, with a carbonate of formula: ##STR1## in which R.sup.1 denotes either a radical of formula ##STR2## in which R.sup.3 and R.sup.4, which may be identical or different, are not hydrogen atoms and denote organic radicals which may be substituted or unsubstituted and saturated or unsaturated, and may be or may not be bound to a polymer, and which can be joined together to form a hetero-cyclic system with the nitrogen atom,or a substituted or unsubstituted aryl radical which may or may not be bound to a polymer,R.sup.2 denotes a hydrogen atom, an aliphatic or cycloaliphatic radical which may be substituted or unsubstituted and saturated or unsaturated, or a substituted or unsubstituted aromatic radical,and X denotes a halogen atom.This process is especially useful for the synthesis of active esters of N-protected amino acids.

Abstract: The invention relates to a process for preparing carbamic acid derivatives of formula: ##STR1## in which R.sup.1 or R.sup.2 denotes a hydrogen atom or a substituted or unsubstituted, saturated or unsaturated aliphatic, cycloaliphatic or heterocyclic radical, or R.sup.1 and R.sup.2 together form a ring, and Y denotes OR, SR, ##STR2## groups, R being a substituted or unsubstituted, saturated or unsaturated aliphatic or cycloaliphatic radical, or a substituted or unsubstituted aromatic radical, R.sup.3 and R.sup.4 denote a hydrogen atom or an aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radical or together form a ring, and R.sup.6 and R.sup.7 denote a saturated or unsaturated, substituted or unsubstituted aliphatic or cycloaliphatic radical, a hydrogen atom, an alkylthio radical or an alkyloxy radical.According to the process, a compound of formula ##STR3## is reacted with an .alpha.-halogenated derivative of formula ##STR4## at a temperature of -5.degree. to 150.degree. C.

Abstract: The invention relates to new .alpha.-chlorinated carbonates characterized in that their formula is: ##STR1## in which X is a fluorine, chlorine or bromine atom and R.sup.1 is different from the ##STR2## group and represents; a substituted or non-substituted, saturated or unsaturated, aliphatic, araliphatic, primary, secondary, tertiary or cycloaliphatic radical.These .alpha.-chlorinated carbonates are prepared by the action of a compound of formula R.sup.1 OH on a chloroformate of formula: ##STR3## in a solvent medium in the presence of an acid scavenger which is added after the two preceding compounds.They are used to block the amine function of amino acids. The .alpha.-chlorinated carbonate and amino acid are reacted in a solvent medium at a temperature of -5.degree. to 100.degree. C. in the presence of an acid scavenger. Blocked amines are very useful in peptide synthesis.