| 摘要 |
In processes for the manufacture of peptides in which one or more free amino groups are protected by conversion into N-(cycloalk-2-en-1-one-3-yl) groups (cf. Specification 1,082,524), the protecting groups are later hydrolysed by treating the peptide derivative with nitrous acid and treating the resulting N-(2-isonitrosocycloalkan - 1 - one - 3 - ylidene) in an aqueous medium of pH less than 6. Peptides containing amino and azido groups may be obtained by applying the nitrous acid treatment to peptides containing amino and hydrazino groups. The nitrous acid may be taken as such or formed in the reaction mixture from an alkali-metal nitrite and an acid. The protecting N-(cycloalk-2-en-1-one-3-yl) group may be introduced by treating the peptide with a 1,3-cycloalkanedione, particularly a 1,3-cyclohexanedione or a 1,3-cyclopentanedione, a number of both of which are specified. The process is applicable to peptides containing carboxylic acid groups, which may be esterified, and when the carboxylic groups are present as benzyl esters they may be converted into the free acids by hydrogenation, as described in Specification 1,082,524. In one example, N - (5,5 - dimethylcyclohex - 2 - en-1- one - 3 - yl) - glycyl - DL - alanine benzyl ester is treated with sodium nitrite and hydrochloric acid to yield glycyl-DL-alanine benzyl ester, which may be hydrogenated to yield glycyl-DL-alanine. In another example, the hydrazide of N - (5,5 - dimethylcyclohex - 2 - en - 1 - one-3-yl) glycyl-glycyl-glycine is treated similarly to yield the hydrochloride of glycyl-glycyl-glycine azide. Other examples are given also. |
