AUTHOR=Benzi Alice , Lopes Susana M. M. , Nunes Sandra C. C. , Giorgi Gianluca , Bianchi Lara , Tavani Cinzia , Pais Alberto A. C. C. , Petrillo Giovanni , Pinho e Melo Teresa M. V. D. 

TITLE=Reactivity of ethyl nitrosoacrylate toward pyrrole, indole and pyrrolo[3,2-c]carbazole: an experimental and theoretical study

JOURNAL=Frontiers in Chemistry

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1229669

DOI=10.3389/fchem.2023.1229669

ISSN=2296-2646

ABSTRACT=<p>Nitrosoalkenes react with 8-methyl-1,6-dihydropyrrolo[3,2-<italic>c</italic>]carbazole to give both 2- and 3-alkylated products via hetero-Diels-Alder reaction followed by the cycloadduct ring-opening. Quantum chemical calculations, at DFT level of theory, were carried out to investigate the regioselectivity of the cycloaddition of ethyl nitrosoacrylate with 1,6-dihydropyrrolo[3,2-<italic>c</italic>]carbazoles as well as with pyrrole and indole, allowing a more comprehensive analysis of the reactivity pattern of nitrosoalkenes with five-membered heterocycles. Furthermore, theoretical calculations confirmed that ethyl nitrosoacrylate reacts with these heterocycles via a LUMO<sub>heterodiene</sub>-HOMO<sub>dienophile</sub> controlled cycloaddition. The reactivity of one of the oxime-functionalized 1,6-dihydropyrrolo[3,2-<italic>c</italic>]carbazole was explored and a new hexahydropyrido[4′,3':4,5]pyrrolo[3,2-<italic>c</italic>]carbazole system was obtained in high yield via a one-pot, two-step procedure.</p>