Palladium‐Catalyzed Cascade to Benzoxepins by Using Vinyl‐Substituted Donor–Acceptor Cyclopropanes

A palladium‐catalyzed intermolecular cascade (4+3) cyclocondensation of salicylaldehydes and vinylcyclopropanes is reported. A key feature of the reaction is the use of a phosphonate group as an acceptor moiety on the cyclopropane, exploiting its propensity to undergo olefination with aldehydes. Sub...

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Bibliographic Details
Published in:Angewandte Chemie 2021-06, Vol.133 (26), p.14531-14535
Main Authors: Faltracco, Matteo, Vrande, Koen N. A., Dijkstra, Martijn, Saya, Jordy M., Hamlin, Trevor A., Ruijter, Eelco
Format: Article
Language:English
Subjects:
Aldehydes
Allyl compounds
benzoxepins
cascade reactions
Chemical reactions
Chemistry
Cyclopropane
Enantiomers
olefination
Organic compounds
Palladium
Phosphonates
seven-membered rings
Substitutes
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Summary:A palladium‐catalyzed intermolecular cascade (4+3) cyclocondensation of salicylaldehydes and vinylcyclopropanes is reported. A key feature of the reaction is the use of a phosphonate group as an acceptor moiety on the cyclopropane, exploiting its propensity to undergo olefination with aldehydes. Subsequent O‐allylation enabled the formation of a range of substituted benzoxepinsWith a novel chiral ligand, the products were obtained in generally good yield and with reasonable enantioselectivity. Enantiomerically enriched benzoxepins were synthesized from phosphonate‐functionalized vinylcyclopropanes and salicylaldehydes by palladium‐catalyzed ring opening followed by Horner–Wadsworth–Emmons olefination and subsequent O‐allylation (see scheme). In contrast to existing cycloaddition reactions of donor–acceptor cyclopropanes, the two bonds are each formed in a separate event, thus allowing greater flexibility in reaction design.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.202102862