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Synthesis of Alkyl‐Substituted Pyrazine N ‐Oxides by Transition‐Metal‐Free Oxidative Cross‐Coupling Reactions
Author(s) -
Lai Miao,
Li Yuan,
Wu Zhiyong,
Zhao Mingqin,
Ji Xiaoming,
Liu Pengfei,
Zhang Xiaoping
Publication year - 2018
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201800183
Subject(s) - pyrazine , chemistry , alkyl , yield (engineering) , thermogravimetric analysis , transition metal , pyrolysis , organic chemistry , coupling reaction , medicinal chemistry , polymer chemistry , catalysis , materials science , metallurgy
Abstract Direct access to alkyl‐substituted pyrazine N ‐oxides has been accomplished through an intermolecular dehydrogenative cross‐coupling reaction of ethers and pyrazine N ‐oxides in the presence of tert ‐butyl hydroperoxide (TBHP). This approach successfully provided a variety of alkyl‐substituted pyrazine N ‐oxides in up to 96 % yield. Thermogravimetric analysis indicates that the degradation temperature of C2‐alkyated product 3 a is approximately 263 °C. Under pyrolysis conditions, 3 a generated several compounds such as 2,5‐dimethylpyrazine, 2,3,5‐trimethylpyrazine, and 3‐ethyl‐2,5‐dimethylpyrazine, which are characterized by their distinct aromas. The results of the pyrolysis experiment support the use of these compounds as possible flavor additives.