TY - JOUR

T1 - N-Pyridylureas as Masked Isocyanates Fort the Late-Stage Diversification of Pyridine-N-Oxides

AU - Байкова, Светлана Олеговна

AU - Байков, Сергей Валентинович

AU - Гейль, Кирилл Константинович

AU - Толстой, Петр Михайлович

AU - Боярский, Вадим Павлович

PY - 2024/3/27

Y1 - 2024/3/27

N2 - A new method for the synthesis of pyridine‐ and quinoline‐ N ‐oxides containing a ureido or carbamoyl fragment in position 2 has been developed. This method concluded in the oxidation of relatively readily available substituted N , N ‐dimethyl‐ N ′‐(pyridine‐2‐yl)ureas to the corresponding N ‐oxides, followed by modification of the dimethylureide moiety. Being heated to 90 °C in the presence of amines in a solution of DMF or chlorobenzene, N ‐oxide of N , N ‐dimethyl‐ N ′‐(pyridine‐2‐yl)urea undergoes a transamination reaction without loss of the N ‐oxide function. This produces N ‐oxides of N ‐alkyl/aryl‐ N’ ‐(pyridine‐2‐yl)ureas in 24–99 % yields, (about 30 examples). Values of the NH protons chemical shifts are a good criterion for the selectivity of the reaction. The reaction is also applicable to N ‐oxides of ureas substituted in the pyridine ring and to the quinoline congener. N ‐Oxides of pyridine/quinoline‐containing carbamates can be similarly prepared by heating N ‐oxides of N , N ‐dimethyl‐ N ′‐(pyridine‐2‐yl)/(quinoline‐2‐yl)‐urea in an appropriate alcohol solution at 120 °C.

AB - A new method for the synthesis of pyridine‐ and quinoline‐ N ‐oxides containing a ureido or carbamoyl fragment in position 2 has been developed. This method concluded in the oxidation of relatively readily available substituted N , N ‐dimethyl‐ N ′‐(pyridine‐2‐yl)ureas to the corresponding N ‐oxides, followed by modification of the dimethylureide moiety. Being heated to 90 °C in the presence of amines in a solution of DMF or chlorobenzene, N ‐oxide of N , N ‐dimethyl‐ N ′‐(pyridine‐2‐yl)urea undergoes a transamination reaction without loss of the N ‐oxide function. This produces N ‐oxides of N ‐alkyl/aryl‐ N’ ‐(pyridine‐2‐yl)ureas in 24–99 % yields, (about 30 examples). Values of the NH protons chemical shifts are a good criterion for the selectivity of the reaction. The reaction is also applicable to N ‐oxides of ureas substituted in the pyridine ring and to the quinoline congener. N ‐Oxides of pyridine/quinoline‐containing carbamates can be similarly prepared by heating N ‐oxides of N , N ‐dimethyl‐ N ′‐(pyridine‐2‐yl)/(quinoline‐2‐yl)‐urea in an appropriate alcohol solution at 120 °C.

UR - https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/slct.202400720

UR - https://www.mendeley.com/catalogue/09ff953c-9b6e-3d56-ad5f-deb751bd0090/

U2 - 10.1002/slct.202400720

DO - 10.1002/slct.202400720

M3 - Article

VL - 9

JO - ChemistrySelect

JF - ChemistrySelect

SN - 2365-6549

IS - 13

M1 - e202400720

ER -