Amine guanidinylation reagents

Because of the enhanced electrophUidty of the amidine carbon in A,A -bis(alkoxycarbon-yl)carboximidamide derivatives, the A,A -bis(fert-butoxycarbonyl)-l//-benzotriazole-l-carboximidamide and A(A -bis(ferf-butoxycarbonyl)-6-nitro-l//-benzotriazole-l-carboximid-amide derivatives were proposed. The latter compound proved to be the most reactive guanidinylating reagent for sterically hindered amines in solution and on solid support. 

L3-Bis(/m-butoxycarbonyl)-2-trifluoromethylsuifonylguanidine and the corresponding Cbz equivalent are a new class of guanidinylation reagents capable of reacting with primary and secondary amines to afford the diprotected guanidine derivatives [Scheme 8.255]. ° Difficulties are only observed with highly steri-cally hindered amines. 

Scheme 4.4). Other reagents useful for terminal guanidinylation of primary and secondary amines have been reported, in which 5-methylisothiourea [15], protected guanidine [16], pyrazole-l-carboxamidine [17] and benzotriazole-1-carboxamidine derivatives [18] are explored. A solid support-linked guanidinylating reagent, consisted of a urethane-protected... 

Scheme 4.4 Preparationof monosubstituted acyclic guanidine 8 and selected guanidinylating reagents of amines...

Zapf, C.W., Creighton, C.J., Tomioka, M. and Goodman, M. (2001) A novel traceless resin-bound guanidinylating reagent for secondary amines to prepare A,A-disubstituted guanidines. Organic Letters, 3, 1133-1136. 

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