Patent GB-876571-A (GB)
Title: New polypeptides and derivatives thereof and the manufacture thereof
Filed: 1957-09-05
Abstract: The invention comprises the octapeptides L-asparaginyl-L-a -amino (amino-lower alkyl)-acetyl-L-a -amino-lower alkyl-acetyl-L-tyrosyl-L-a - amino lower alykyl-acetyl-L- histidyl-L-prolyl-L-phenylalanines and derivatives thereof having an esterified carboxyl group, free amino groups and a substituted hydroxy group, or having an esterified carboxyl group, a free or substituted hydroxy group and an a -amino-(amino-lower alkyl)-acetyl radical in which the amino-lower alkyl residue is protected by a protecting group and the a -amino group is protected, the protecting group being capable of being split off by hydrogenation or hydrolysis, and L-aspartyl-L-a -amino-(amino-lower alkyl)-acetyl-L- a -amino lower alkyl-acetyl-L-tyrosyl-L-leucine- L-histidyl-L-prolyl-L -phenylalanines, and salts of all these octapeptides, and the preparation thereof by reacting amino-acids so that there are linked together in an amide like manner the residues of L-asparagine having the amino group protected by a group capable of being split off by hydrogenation or hydrolysis, of L-a -amino-(amino-lower L-a -amino-(amino-lower alkyl)-acetic acid having the amino group of the amino-alkyl radical protected by a group which is capable of being split off by hydrogenation or hydrolysis, of L-a -amino-lower alkyl acetic acid, of L-tyrosine having a free or substituted hydroxy group, of L-a -amino-lower alkyl-acetic acid, of L-histidine, of L-proline, and of L-phenylalanine ester to form an octapeptide having the above amino-carboxylic acid radicals in the sequence indicated and, when required, treating the octapeptide so obtained to liberate a carboxyl group from the esterified carboxyl group of the phenylalanine radical, an amino group from the protected amino group of the asparagine radical or of the L-a -amino-(amino-lower alkyl) acetyl radical and, when required, a hydroxyl group from the substituted hydroxy group of the tyrosine radical and, if desired, converting the carbonylamide group of the L-asparagine radical into a free carboxyl group to form the L-aspartyl radical. The lower alkyl radicals each contain up to 4 carbon atoms.  The invention also comprises L-valyl-L-tyrosyl-L-valyl-L-histidyl-L-prolyl-L-phenylalanine and derivatives thereof having esterified carboxyl groups and a free or protected amino group, said protecting group being capable of being split off by hydrogenation or hydrolysis, and salts of these compounds; L-leucyl-L-tyrosyl-L-isoleucyl-L-histidyl-L-prolyl-L-phenylalanine and derivatives thereof having an esterified group and a free or protected amino group, said protecting group being capable of being split off by hydrogenation or hydrolysis, and salts of these compounds; L-valyl-L-tyrosyl-L-leucyl-L-histidyl-L-prolyl-L-phenylalanine and derivatives thereof having an esterified carboxyl group and a free or protected amino group, said protecting group being capable of being split off by hydrogenation or hydrolysis, and salts of these compounds; L-isoleucyl-L-histidine hydrazide and L-isoleucyl-L-histidine esters in which compounds the amino group is protected by a group which is capable of being split off by hydrogenation or hydrolysis, and salts of these compounds; L-leucyl-L-histidine hydrazide and L-leucyl-histidine esters in which compounds the amino group is protected by a group which is capable of being split off by hydrogenation or hydrolysis, and salts of these compounds; L-prolyl-L-phenylalanine esters and salts thereof; L-asparaginyl-N-e -carbobenzyloxy-L-lysine the free amino group of which is protected by a group capable of being split off by hydrogenation or hydrolysis, and esters thereof, and salts of these compounds L-leucyl-L-tyrosine the free amino group of which is protected by a group capable of being split off by hydrogenation or hydrolysis, and esters thereof, and salts of these compounds; L-asparaginyl-nitro-L-arginyl-L-valyl-L-tyrosine the free amino group of which is protected by a group capable of being split off by hydrogenation or hydrolysis, and salts of these compounds; L-isoleucyl-L-histidyl-L-prolyl-L-phenylalanine and derivatives thereof having an esterified carboxyl group and a free or protected amino group said protecting group being capable of being split off by hydrogenation or hydrolysis, and salts of these compounds; L-leucyl-L-histidyl- L-prolyl- L-phenylalanine and derivatives thereof having an esterified carboxyl group and a free or protected amino group, said protecting group being capable of being split off by hydrogenation or hydrolysis, and esters thereof, and salts of these compounds.  Radicals that may be used to protect the free amino groups are the carbobenzyloxy and trityl radicals.  In the octapeptides referred to above, the a -amino-(amino-lower alkyl)-acetyl radicals may be derived from arginine, lysine, ornithine, a ,g -diamino-butyric acid or citrulline, and the a -amino-lower alkyl-acetyl radicals in the third and fifth positions of the octapeptide may be the same or different and may be derived from valine, nor-valine, leucine, iso-leucine, nor-leucine or alanine.  The amino-group of the lower alkyl group in the above mentioned a -amino-(amino-lower alkyl)-acetyl group may be substituted, e.g. by an amidino or carbamyl group (the amino group of the amidino group may be protected in the form of a nitro group, e.g. the nitro-L-arginyl group may be present in the octapeptide).  A free carboxyl group present in the octapeptide product of the above processes may be functionally converted particularly into an ester or amide group, and a free amino group may be alkylated or acylated. The preferred methods for preparing the above octapeptides are (1) reacting nitro-L-arginine with L-asparagine containing a protected amino group and reacting the resulting L-asparaginyl-nitro-L-arginine with either an L-a -amino-lower alkyl-acetyl-L-tyrosyl-L-a -amino-lower alkyl-acetyl-L-histidyl-L-prolyl-L-phenylalanine ester or with an L-a -amino-lower alkyl-acetyl-L-tyrosine to form an asparaginyl-nitro- L-arginyl- L-a -amino-lower alkyl-acetyl-L-tyrosine and reacting this compound with L-a -amino-lower alkyl-acetyl-L-histidyl-L-prolyl-L-phenylalanine ester; and (2) reacting L-a -amino-lower alkyl acetyl-L-tyrosyl-L-a -amino lower alkyl-acetyl-histidine with an L-asparaginyl-nitro-L-arginine and reacting the resulting L-asparaginyl-nitro-L-arginyl-L-a -amino-lower alkyl-acetyl-L-tyrosyl-L-a -amino-lower alkyl-acetyl- L-histidine with L-prolyl-L-phenylalanine.  In the preferred methods (1) and (2) above, the first L-a -amino-lower alkyl acetic acid may be condensed with L-tyrosine to form an L-a -amino-lower alkyl-acetyl-L-tyrosine and with L-histidine to form an L-a -amino-lower alkyl-acetyl-L-histidine and L-proline may be condensed with L-phenylalanine ester to form the L-prolyl-L-phenylalanine ester, the L-a -amino-lower alkyl-acetyl-L-histidine is then acylated with L-a -amino-lower alkyl-acetyl-L-tyrosine to form the L-a -amino-lower alkyl-acetyl-L-tyrosyl-L-a -amino-lower alkyl-acetyl-L-histidine; alternatively the L-a -amino-lower alkyl-acetic acid may be condensed with the L-a -amino-lower alkyl-acetyl-L-tyrosine to form the L-a -amino-lower alkyl-acetyl-L-tyrosyl-L-a -amino-lower alkyl acetic acid which is then condensed with L-histidine.  In the preferred methods (1) and (2) and in the reactions by which reactants for these preferred methods are prepared; free amino groups not taking part in the reaction must be protected by means of radicals which may be split off by hydrogenation or hydrolysis.  Thus Ne -carbobenzyloxy-L-lysine may be acylated with an L-asparagine containing a protected amino group.  The amino-acids to be acylated are advantageously used in the form of their esters.  The above processes may be modified in that an intermediate product obtained at any stage of the process may be used as the starting compound and the remaining stages are then carried out.  The acylation steps may be carried out by reacting the acid with the corresponding phosphite amide, e.g. the diethyl p  phosphite amide, by reacting the acid with the amine in the presence of 1-cyclohexyl- 3-(2-morpholinyl- (4)-ethyl) carbo-di-imide, and by reacting the amine with an active ester in which there is a cyano or nitro group as an activating substituent in the alcohol.  In the examples the following compounds are prepared:-N-carbobenzyloxy-L-asparaginyl-nitro-L-arginine and the methyl ester thereof, N-carbobenzyloxy-L-asparaginyl-nitro-L-arginyl-L-valyl-L-tyrosine and the methyl ester thereof, N-carbobenzyloxy-L-asparaginyl-nitro- L-arginyl- L-valyl-L-tyrosyl -L-isoleucyl (and leucyl and valyl)-L-histidyl-L-prolyl-L-phenylalanine methyl ester, L-asparaginyl-L-arginyl-L-valyl- L-tyrosyl- L-isoleucyl (and leucyl and valyl)-L-histidyl-L-prolyl-L-phenylalanine and the methyl ester thereof, L-aspartyl-L-arginyl-L-valyl- L-tyrosyl-L-isoleucyl (and leucyl and valyl)-L-histidyl-L-prolyl- L-phenylalanine, N-carbobenzyloxy-L-valyl-tyrosine methyl ester, L-valyl-L-tyrosine methyl ester, N-carbobenzyloxy-L-isoleucyl (and leucyl)-L-histidine methyl ester, N-carbobenzyloxy-L- isoleucyl (and leucyl)-L-histidine hydrazide (obtained by the reaction of the corresponding methyl esters and hydrazine), N-carbobenzyloxy-L-prolyl-L-phenylalanine methyl ester, L-prolyl-L-phenylalanine methyl ester, N-carbobenzyloxy -L-isoleucyl (and leucyl)-L-histidyl-L-prolyl-L-phenylalanine methyl ester, L-isoleucy (and leucyl)-L-histidyl-L-prolyl-L-phenylalanine and the methyl ester thereof, N-carbobenzyloxy-L-asparaginyl-nitro- L-arginyl-L-valyl-L-lyrosyl -L-valyl-L-histidyl-L-prolyl-L-phenylalanine methyl ester, N-carbobenzyloxy- L-valyl- L-tyrosyl- L-valyl (and leucyl)- L-histidyl- L-prolyl- L-phenylalanine methyl ester, L-valyl-L-tyrosyl-L-valyl (and leucyl)- L-histidyl- L-prolyl- L-phenylalanine and the methyl ester thereof, N-carbobenzyloxy-L-valyl-L-tyrosyl-L-valyl-L-histid