Arene Activation through Iminium Ions: Product Diversity from Intramolecular Photocycloaddition Reactions.

Autor: Proessdorf J; Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany., Jandl C; Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany., Pickl T; Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany., Bach T; Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany.
Jazyk: angličtina
Zdroj: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2022 Oct 04; Vol. 61 (40), pp. e202208329. Date of Electronic Publication: 2022 Sep 02.
DOI: 10.1002/anie.202208329
Abstrakt: While 2-alk-ω-enyloxy-sustituted benzaldehydes do not display any photochemical reactivity at the arene core, the respective iminium perchlorates were found to undergo efficient reactions either upon direct irradiation (λ=366 nm) or under sensitizing conditions (λ=420 nm, 2.5 mol% thioxanthen-9-one). Three pathways were found: (a) Most commonly, the reaction led to benzoxacyclic products in which the olefin in the tether underwent a formal, yet unprecedented carboformylation (13 examples, 44-99 % yield). The cascade process occurred with high diastereoselectivity and was found to be stereoconvergent. (b) If a substituent resides in the 3-position of the benzene ring, a meta photocycloaddition was observed which produced tetracyclic skeletons with five stereogenic centers in excellent regio- and diastereoselectivity (2 examples, 58-79 % yield). (c) If the tether was internally substituted at the alkene, an arene photocycloaddition was avoided and an azetidine was formed in an aza Paternò-Büchi reaction (2 examples, 95-98 % yield).
(© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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