Conversion of N,N′-bis(tert-butoxycarbonyl)guanidines to N-(N′-tert-butoxycarbonylamidino)ureas

Macrocyclization of Di‐Boc‐guanidino‐alkylamines Related to Guazatine Components: Discovery and Synthesis of Innovative Macrocyclic Amidinoureas

“…Linear amidinoureas have been previously prepared by Rault and Miel through cross reaction of tri-Boc-or di-Boc-guanidines with different amines under mild conditions and in the presence of a base. [6] The authors also proposed that their formation could proceed via an isocyanate intermediate, [6a] formed from the Bocprotecting group by an E1cB mechanism with a conjugate base and subsequent addition of external amines as nucleophilic agents.…”

“…Linear amidinoureas have been previously prepared by Rault and Miel through cross reaction of tri-Boc-or di-Boc-guanidines with different amines under mild conditions and in the presence of a base. [6] The authors also proposed that their formation could proceed via an isocyanate intermediate, [6a] formed from the Bocprotecting group by an E1cB mechanism with a conjugate base and subsequent addition of external amines as nucleophilic agents. [2b] Since in our cases no external conjugate bases are present in the reaction mixtures, we hypothesised that the amino group of aminoguanidines 2 could work both as the conjugate base in the formation of the isocyanate intermediate and as the nucleophilic agent.…”

“…[2a, 5,6] However, no examples of cyclic or macrocyclic amidinoureas are known so far. The design and synthesis of macrocyclic structures with an appropriate ring size and predictable function is an important research topic and still remains an attractive challenge in organic synthesis.…”

A versatile synthesis of 2‐amino‐4H‐pyrido[1,2‐a][1,3,5]triazin‐4‐ones from 2‐aminopyridines

“…On our part, with the aim of building guanidine libraries of medicinal chemistry interest, we studied the total deprotection of bis Boc-guanidines using SnCl 4 [23], and also their conversion to N-Boc-amidinoureas by reaction with amines [24] (Scheme 2).…”

Triazine‐Based Highly Stable AADD‐Type Self‐Complementary Quadruple Hydrogen‐Bonded Systems Devoid of Prototropy

“…This is the most crucial step in the synthetic scheme, because it involves the formation of triazine ring fea- turing tert-butyl carbamate, as urrogate of isocyanate, which can be further reacted with amines under basic condition to form substituted ureas. [16] Thus, withouti solating the isocyanate intermediate, 5 was exposed to base in the presence of amines to complete the synthesis of AADD-type self-assembling systems 1a-f in good yields.…”