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.