Expanded Chemistry of Formamidine Ureas

Abstract

[reaction: see text] Formamidine ureas display a rich manifold of reactivity. Thiols induce substitution at the carbonyl carbon to give thiolcarbamates; base-mediated alkylation and acylation occurs at the terminal urea nitrogen, and a new fragmentation/acylation pathway has been uncovered with isocyanates.

Structural and vibrational study of 2‐(2′‐ furyl)‐4,5‐1H‐dihydroimidazole

“…As predicted by elemental organic chemistry bonding rules, in the furyl group the formally double C6C7 and C8C9 bonds [lengths of 1.336(3) and 1.323(3) Å, respectively] have been found to be shorter than the formally single C7C8 bond [1.413(3) Å], which is in agreement with the corresponding bond lengths reported for the parent furan molecule53 and with another compound containing the furan ring 54. Similarly, in the 4,5‐1 H ‐dihydroimidazole group, the formally double C2N3 bond [1.281(2) Å] is shorter than the C2N1 single bond [1.359(2) Å] as found in other 4,5‐1 H ‐dihydroimidazole containing substances 55, 56…”

Acyclic and Cyclic Ureas (Update 2013)

“…[304] Scheme 117 Exchange of the Imine Component in N-(Iminomethyl)ureas [303] Other useful transformations of N-(iminomethyl)ureas include the synthesis of thiocarbamates by reaction with thiols and base-mediated alkylation and acylation. [305] With isocyanates in the presence of strong bases, N-(iminomethyl)ureas incorporating the isocyanate substituents in place of the original urea are the major isolable products. …”

Cerium (IV) Ammonium Nitrate (CAN) Mediated Reactions IV. A Highly Efficient Synthesis of N,N’-Diarylsubstituted Formamidines in Water at Ambient Temperature

“…This approach suffers from drawbacks of high temperatures and the use of protic organic solvents (mostly methanol or ethanol) for a period of 1 -48 hours [22]. The beneficial effect of base in non-protic solvents for this transformations has also been reported [23]. A revisiting of the effect of acid in the amine exchange of N,N -dimethylformamidines has been recently reported [18] which allowing the preparation of highly electron-rich compounds that are difficult to obtain under standard conditions.…”