Wang, Mingliang et al. published their research in Tetrahedron Letters in 2018 | CAS: 2387-23-7

1,3-Dicyclohexylurea (cas: 2387-23-7) belongs to amides. Because of the greater electronegativity of oxygen, the carbonyl (C=O) is a stronger dipole than the N–C dipole. The presence of a C=O dipole and, to a lesser extent a N–C dipole, allows amides to act as H-bond acceptors. Amides are not in general accessible by the direct condensation of amines with carboxylic acids for two reasons: first, both components are readily deactivated by a transfer of a proton from the acid to the amine and second, the hydroxy unit on the carbonyl of the acid is a relatively poor leaving group. Nevertheless, the formation of five- and six-membered rings is often surprisingly simple provided that other factors can be brought into play to assist in the condensation.Reference of 2387-23-7

Effective approach to ureas through organocatalyzed one-pot process was written by Wang, Mingliang;Han, Jilai;Si, Xiaojia;Hu, Yimin;Zhu, Jidong;Sun, Xun. And the article was included in Tetrahedron Letters in 2018.Reference of 2387-23-7 This article mentions the following:

An efficient approach to N,N’-unsym. substituted ureas ArN(R1)C(O)NH(R2) (R1 = H; R2 = n-Bu, c-hexyl, Bn, etc.; Ar = 4-MeC6H4, 4-MeOC6H4, 4-F3CC6H4, 3-BrC6H4) has been developed through the ammonolysis of N-Boc protected anilines with amines prompted by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). Moreover, a convenient protocol for the synthesis of the sym. N,N’-substituted ureas RNHC(O)NHR (R = Ph, 2-ClC6H4, 4-IC6H4, etc.) by one-pot diammonolysis of Boc2O with amines catalyzed by DABCO has also been achieved. With broad substrate scope and mild conditions, these two methods demonstrate practical preparation of both unsym. and sym. ureas. In the experiment, the researchers used many compounds, for example, 1,3-Dicyclohexylurea (cas: 2387-23-7Reference of 2387-23-7).

1,3-Dicyclohexylurea (cas: 2387-23-7) belongs to amides. Because of the greater electronegativity of oxygen, the carbonyl (C=O) is a stronger dipole than the N–C dipole. The presence of a C=O dipole and, to a lesser extent a N–C dipole, allows amides to act as H-bond acceptors. Amides are not in general accessible by the direct condensation of amines with carboxylic acids for two reasons: first, both components are readily deactivated by a transfer of a proton from the acid to the amine and second, the hydroxy unit on the carbonyl of the acid is a relatively poor leaving group. Nevertheless, the formation of five- and six-membered rings is often surprisingly simple provided that other factors can be brought into play to assist in the condensation.Reference of 2387-23-7

Referemce:
Amide – Wikipedia,
Amide – an overview | ScienceDirect Topics