Abstract: Ureins are obtained by reaction, in basic medium, between an N&ohgr;-(aryloxycarbonyl)diamino acid and a compound containing a free amino group. The chirality of the compounds is outstandingly well preserved.

Abstract: Ureins are obtained by reaction, in basic medium, between an N&ohgr;-(aryloxycarbonyl)diamino acid and a compound containing a free amino group. The chirality of the compounds is outstandingly well preserved.

Abstract: Ureins are obtained by reaction, in basic medium, between an N.sup..omega. -(aryloxycarbonyl)diamino acid and a compound containing a free amino group. The chirality of the compounds is outstandingly well preserved.

Abstract: Compounds having the general formula: ##STR1## in which R3 represents an aryl group which is unsubstituted or substituted by one or more alkyl groups containing 1 to 4 carbon atoms; R4 represents a hydrogen atom, a group for protecting the amino functional group, an amino acid or a peptide some of whose functional groups are optionally substituted by a protecting group or by an activating group; R5 represents a hydroxy group, a halogen atom, a group for protecting the carboxyl functional group, an activating group, an amino group, an amino acid or a peptide some of whose functional groups are optionally substituted by a protecting group or by an activating group; and n is an integer from 1 to 10.

Abstract: Method of synthesising peptides containing one or more amino acid residues bearing an N-carbamoyl functional group, by aminolysis of N-aryloxycarbonyl derivatives, which are excellent synthesis intermediates for the preparation of various peptides containing amino acid residues bearing a ureino group, such as citrulline, homocitrulline, 2-amino-4-ureidobutyric residues.

Abstract: An .alpha.-amino acid amide is prepared by reaction of an N.sup..alpha. -aryloxycarbonylamino acid with a compound containing a free amino group. This process makes it possible readily to prepare peptides, by direct reaction between the carboxyl group of the N.sup..alpha. -aryloxycarbonyl derivative of an amino acid and the free amino group of a second amino acid or of a peptide fragment, without requiring protection of the carboxyl function of the second amino acid or of the peptide fragment, nor a coupling agent nor a deprotection step.

Abstract: A compound useful in the synthesis of peptides containing arginine, and including a guanidine group and an unsubstituted tetraphenylborate ion, and having the formula: ##STR1## wherein A is a hydrogen atom, an amino acid group which is linked by a peptide bond and which may be substituted, a peptide radical which is linked by a peptide bond and which may be substituted, or an aliphatic or aromatic radical effective as a protecting group or an activating group, and wherein Y is an hydroxyl group, a halogen atom, an amino group, an amino acid group which is linked by a peptide bond and which may be substituted, a peptide radical which is linked by a peptide bond and which may be substituted, or an aliphatic or aromatic radical effective as a protecting group or an activating group.

Abstract: Use of a guanidine-related compound in solution phase peptide synthesis, the guanidine-related compound including a tetraphenylborate ion and having the general formula: ##STR1## wherein R denotes an organic radical including at least one amine group, and R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 denote inorganic or organic groups independently of each other.

Abstract: Use of a guanidine-related compound in solution phase peptide synthesis, the guanidine-related compound comprising a tetraphenylborate ion and having the general formula: ##STR1## wherein R denotes an organic radical comprising at least one amine group.