20885-44-3Relevant academic research and scientific papers
Synthesis of unsymmetrical urea from aryl- or pyridyl carboxamides and aminopyridines using PhI(OAc)2via in situformation of aryl- or pyridyl isocyanates
Hunjan, Mandeep Kaur,Laha, Joydev K.,Singh, Neha
, p. 18815 - 18823 (2021/10/26)
A tandem synthesis of unsymmetrical ureas (N-aryl-N′-pyridylurea andN,N′-bipyridylurea) from aryl- or pyridyl carboxamides and aminopyridinesviaHofmann rearrangement has been reported. In particular, benzamides, picolinamide, nicotinamide, and isonicotinamide generate reactive intermediate isocyanates,in situ, in the presence of PhI(OAc)2, which upon further reaction with aminopyridines form urea derivatives. As the formation of pyridylisocyanates from their corresponding carboxamidesviaHofmann rearrangement remained unexplored previously, attempts have been made to trap the isocyanates. While the three pyridylisocyanates were trapped as their corresponding carbamates, 3-pyridylisocyanate was isolated and characterized. Unlike closely related previous methods reported for urea synthesis, the current method avoids direct use of isocyanates or eliminates the use of toxic phosgene for thein situgeneration of isocyanates.
Metal-free synthesis of pyridin-2-yl ureas from 2-aminopyridinium salts
Saroj,Patel, Om P.S.,Rangan, Krishnan,Kumar, Anil
, (2019/07/23)
An unprecedented base promoted domino approach has been developed for the synthesis of pyridin-2-yl urea derivatives via the reaction of 2-aminopyridinium salts and arylamines. The developed strategy tolerated a wide range of functional groups and afforded pyridin-2-yl ureas in moderate to good yields. The reaction was postulated to involve tandem cyclization, intermolecular nucleophilic addition, ring opening, and demethylation.
Substituent Effects on Pyrid-2-yl Ureas toward Intramolecular Hydrogen Bonding and Cytosine Complexation
Chien, Chia-Hui,Leung, Man-Kit,Su, Jen-Kuan,Li, Gene-Hsiang,Liu, Yi-Hung,Wang, Yu
, p. 1866 - 1871 (2007/10/03)
Equilibria between two conformational isomers of pyrid-2-yl ureas, the (E,Z) and (Z,Z) forms, have been studied in DMF-d7 at -70 °C. Most of them show a small preference for the (E,Z) form with an equilibrium constant Ki around 1-2. However, the Ki value for 1-methyl-2-(3-(pyrid-2-yl)ureido)pyridinium iodide (12) was found to be 14.2 ± 1.2. That is 1 order of magnitude larger than those of the others, which indicates that the positively charged 1-methylpyridinium-2-yl substituent would facilitate the (E,Z) form formation. Pyrid-2-yl ureas bind cytosine in DMF-d7 with binding constants KB ranging from 30 to 1700 M-1. Electron withdrawing substituents, such as the 4-O 2NC6H4- or 1-methylpyridinium-4-yl substituent, preferentially facilitate the intermolecular cytosine complexation with large binding constants.
