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Please login or sign up for a free trial to access the full content. Method 1: From Guanidines

DOI: 10.1055/sos-SD-118-00076

Kubik, S.Science of Synthesis Knowledge Updates, (20133291.

Reaction of the guanidine group in the side chain of an arginine residue with N-succin­imidyl N-methylcarbamate introduces an N-carbamimidoylurea residue into a cyclopeptide side chain.[‌307‌,‌308‌] N,N-Disubstituted N′-aminocarbonyl(benzotriazolyl)carboximid­amides 66 (Scheme 119) yield N-carbamimidoylureas upon reaction with amines, albeit only in low yields (up to 43%).[‌309‌] The major products, sometimes the only products, are di- and trisubstituted ureas. More efficient reagents for the conversion of amines into N-carbamimidoylureas are N-(tert-butoxycarbonyl)-N′-[(4-methoxybenzyl)(methyl)carbamoyl]-1H-pyrazole-1-carboximidamide (67), 1,2-bis(tert-butoxycarbonyl)guanidine (68), and 1,2,3-tris(tert-butoxycarbonyl)guanidine (69).

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