Orthoamide, LXIX [1]. Beiträge zur Synthese N,N,N´,N´,N´´-peralkylierter Guanidine und N,N,N´,N´,N´´䞲,N´´-persubstituierter Guanidiniumsalze / Orthoamides, LXIX [1]. Contributions to the Synthesis of N, N, N´, N´, N´-peralkylated Guanidines and N, N, N´, N´, N´´, N´´-persubstituted Guanidinium Salts

Abstract

N, N, N´, N´-Tetraalkyl-chloroformamidinium chlorides 6 are prepared from N, N, N´, N´-tetraalkylureas 5 and phosgene in acetonitrile. The iminium salts 6 react with primary and secondary amines in the presence of triethylamine to give N, N, N´, N´, N´´-pentasubstituted and N, N, N´, N´, N´´, N´´- hexasubstituted guanidinium salts 7 and 8, respectively, Treatment of the guanidinium salts 7 with sodium hydroxide in excess affords the N, N, N´N´, N´´-pentasubstituted guanidines 9a - 9aa. Additionally, the N, N, N´, N´, N´´-pentasubstituted and N, N, N´, N´, N´´, N´´-hexasubstituted guanidinium salts 7l´, 7p´ and 8a - c can be obtained from the reaction mixtures by addition of stoichiometric amounts of sodium hydroxide. A modified method is described for the preparation of guanidinium salts possessing dialkylamino substituents consisting of two long-chain alkyl groups (>C14). Some guanidines 9 were alkylated with allyl chloride and bromide, ethyl bromide, butyl bromide, benzyl bromide and chloride, dimethyl sulfate, diethyl sulfate, and methyl methansulfonate to give the corresponding guanidinium salts 11 - 15. By alkylation of the N, N, N´, N´, N´´-pentasubstituted guanidine 9v with triethyloxonium tetrafluoroborate the guandinium tetrafluoroborate 16a is accessible. N-Functionalized guanidinium salts 17 - 18a - c result from the reaction of N, N, N´, N´, N´´-pentasubstituted guanidines with ethyl bromoacetate and bromoacetonitrile, respectively, and subsequent anion exchange with sodium tetraphenylborate. N, N, N´, N´-Tetramethylguanidine (21) adds to ethyl acrylate to give the labile guanidine 22, which forms the guanidinium salt 23a on treatment with methyl iodide. Zwitterionic guanidinium salts 25 result, when N, N, N´, N´, N´´-pentasubstituted guanidines are treated with sultones 24.