Method for controlled stepwise synthesis of polypeptides utilizing n-thiocarboxy anhydrides of amino acids as reagents

Claim 2

THE PROCESS FOR THE CONTROLLED STEPWISE SYNTHESIS OF PEPTIDES AND PROTECTED DERIVATIVES THEREOF WHICH COMPRISES REACTING A STARTING AMINO COMPOUND SELECTED FROM THE GROUP CONSISTING OF AMINO ACIDS, PEPTIDES, AND DERIVATIVES THEREOF WHEREIN ADDITIONAL FUNCTIONAL GROUPS ARE PROTECTED WITH A TCA REAGENT SELECTED FROM THE GROUP CONSISTING OF NTHIOCARBOXY AMINO ACID ANHYDRIDES, AND DERIVATIVES THEREOF WHEREIN ADDITIONAL FUNCTIONAL GROUPS ARE PROTECTED, SAID REACTION BEING CONDUCTED BY BRINGING TOGETHER SAID AMINO COMPOUND AND SAID TCA REAGENT IN AN AQUEOUS MEDIUM WHILE MAINTAINING THE PH AT THE PROTECTING PH (WHEREBY THE ONLY AMINO GROUP PRESENT IN APPRECIABLE CONCENTRATION IN REACTIVE FORM DURING THE COURSE OF THE REACTION IS THE AMINO GROUP OF THE STARTING AMINO COMPOUND WHICH IS TO PARTICIPATE IN THE REACTION WITH THE SAID TCA REAGENT) THEREBY FORMING THE CORRESPONDING N-THIOCARBOXY PEPTIDE, AND DETHIOCARBOXYLATING BY ACIDIFICATION, STANDING, HEATING OR FREEZ-DRYING SAID N-THIOCARBOXY PEPTIDE.

Claim 3

The process as defined in claim 1 wherein the reaction is conducted at a protecting pH of from about 4 to about 11.

Claim 4

The process for the controlled stepwise synthesis of peptides and protected derivatives thereof which comprises adding a TCA reagent selected from the group consisting of N-thiocarboxy amino acid anhydrides, and derivatives thereof wherein additional functional groups are protected, to an aqueous medium containing a pH controlling buffer and a starting amino compound selected from the group consisting of amino acids, peptides, and derivatives thereof wherein additional functional groups are protected, under conditions of intimate mixing at a protecting pH of from 4 to 10 (such that the only amino group present in appreciable concentration in reactive form during the coUrse of the reaction is the amino group of the starting amino compound which is to participate in the reaction with the said TCA reagent) thereby forming the corresponding N-thiocarboxy peptide, and reacting resulting peitide (following dethiocarboxylation by acidification, standing, heating or freeze-drying) with TCA reagent as defined hereinabove under reaction conditions as aforesaid.

Claim 5

The process for the controlled stepwise synthesis of peptides and protected derivatives thereof which comprises adding a TCA reagent selected from the group consisting of N-thiocarboxy amino acid anhydrides, and derivatives thereof wherein additional functional groups are protected, to an aqueous medium containing a pH controlling buffer and a starting amino compound selected from the group consisting of amino acids, peptides, and derivatives thereof wherein additional functional groups are protected, under conditions of intimate mixing at a protecting pH of from 4 to 10 (such that the only amino group present in appreciable concentration in reactive form during the coUrse of the reaction is the amino group of the starting amino compound which is to participate in the reaction with the said TCA reagent) thereby forming the corresponding N-thiocarboxy peptide, and reacting resulting peitide (following dethiocarboxylation by acidification, standing, heating or freeze-drying) with TCA reagent as defined hereinabove under reaction conditions as aforesaid.

Claim 6

The process as defined in claim 3 wherein the pH controlling buffer is a borate buffer, and wherein the protecting pH, designed for stabilization of the carbamate protecting group, is from about 7.5 to about 10.

Claim 7

The process, as defined in claim 3, for the controlled stepwise synthesis of peptides and protected derivatives thereof which comprises adding a TCA reagent selected from the group consisting of N-thiocarboxy amino acid anhydrides, and derivatives thereof wherein additional functional groups are protected, to an aqueous medium containing a starting amino compound selected from the group consisting of amino acids, peptides, and derivatives thereof wherein additional functional groups are protected, under conditions of intimate mixing at a protecting pH of from 4 to 6 (such that, using protonation to protect amino, the only amino group present in appreciable concentration in reactive form during the source of the reaction is the amino group of the starting amino compound which is to participate in the reaction with the said TCA reagent) thereby forming the corresponding N-thiocarboxy peptide, and reacting resulting peptide (following dethiocarboxylation by acidification, standing, heating or freeze-drying) with TCA reagent as defined hereinabove under reaction conditions as aforesaid.

Claim 8

The process, as defined in claim 3 for the controlled stepwise synthesis of peptides and protected derivatives thereof which comprises adding a TCA reagent selected from the group consisting of N-thiocarboxy amino acid anhydrides, and derivatives thereof wherein additional functional groups are protected, to an aqueous medium containing a starting amino compound selected from the group consisting of amino acids, peptides, and derivatives thereof wherein additional functional groups are protected, under conditions of intimate mixing while concurrently adding sufficient alkaline reagent to said medium to maintain a protecting pH (so that the only amino group present in appreciable concentration in reactive form during the course of the reaction is the amino group of the starting amino compound which is to participate in the reaction with the said TCA reagent) thereby forming the corresponding N-thiocarboxy peptide, and reacting resulting peptide (following dethiocarboxylation by acidification, standing, heating or freeze-drying) with TCA reagent as defined hereinabove under reaction conditions as aforesaid.

Claim 9

The process as defined in claim 1 wherein the reaction is conducted by adding a mixture of said TCA reagent together with said starting amino compound to said aqueous medium under conditions of intimate mixing and at the protecting pH.