Galenko Ekaterina E, Bodunov Vladimir A, Kryukova Mariya A, Novikov Mikhail S, Khlebnikov Alexander F
Saint Petersburg State University, Institute of Chemistry, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia.
J Org Chem. 2021 Mar 5;86(5):4098-4111. doi: 10.1021/acs.joc.0c02928. Epub 2021 Feb 11.
The reaction conditions for the Buchner reaction of 2-(diazoacetyl)-2-azirines with benzene leading to 2-(cyclohepta-2,4,6-trien-1-yl)-2-azirines have been found. The azirine fragment of these compounds was subsequently used to prepare 5-(cyclohepta-2,4,6-trien-1-yl)isoxazoles and α-(cyclohepta-2,4,6-triene-1-ylcarbonyl)-1-pyrroles. NMR and DFT calculations showed that the cycloheptatriene-norcaradiene valence isomerization in the corresponding moieties of synthesized azirines, isoxazoles, and pyrroles is very fast at room temperature. Cycloheptatriene valence isomer predominates in azirines and pyrroles, while 5-(cycloheptatrienyl)isoxazoles exist in a pure cycloheptatriene form at 25 °C in chloroform solution. In accordance with the X-ray analysis, two of the synthesized pyrroles crystallized as norcaradiene isomers from a solution of equilibrium mixture of valence isomers. Reductive isoxazole ring opening using the Mo(CO)/HO reductive system afforded ()-3-amino-3-aryl-1-(cyclohepta-2,4,6-trien-1-yl)prop-2-en-1-ones, which are pure cycloheptatriene isomers. α-(Cycloheptatrieneylcarbonyl)-1-pyrroles were transformed into the α-(benzylcarbonyl)-1-pyrroles under cooperative TFA/Rh(TFA) catalysis.
已发现2-(重氮乙酰基)-2-氮杂环丙烷与苯发生布赫纳反应生成2-(环庚三烯-2,4,6-三烯-1-基)-2-氮杂环丙烷的反应条件。这些化合物的氮杂环丙烷片段随后被用于制备5-(环庚三烯-2,4,6-三烯-1-基)异恶唑和α-(环庚三烯-2,4,6-三烯-1-羰基)-1-吡咯。核磁共振和密度泛函理论计算表明，在合成的氮杂环丙烷、异恶唑和吡咯的相应部分中，环庚三烯-降蒈二烯价键异构化在室温下非常迅速。环庚三烯价键异构体在氮杂环丙烷和吡咯中占主导地位，而5-(环庚三烯基)异恶唑在25℃的氯仿溶液中以纯环庚三烯形式存在。根据X射线分析，两种合成的吡咯从价键异构体平衡混合物溶液中以降蒈二烯异构体形式结晶。使用Mo(CO)/HO还原体系进行的异恶唑环还原开环反应得到了()-3-氨基-3-芳基-1-(环庚三烯-2,4,6-三烯-1-基)丙-2-烯-1-酮，它们是纯环庚三烯异构体。在TFA/Rh(TFA)协同催化下，α-(环庚三烯基羰基)-1-吡咯转化为α-(苄基羰基)-1-吡咯。
