Tandem Photoisomerization and Transannular Cyclizations of Zerumbone Epoxide: A Model for Diversity-Oriented Synthesis Using Abundant Natural Products

Abstract

Photoirradiation of (6E,9E)-zerumbone-2,3-epoxide afforded a diverse range of transannular cyclized products in the presence of a catalytic amount of Sc(OTf) 3 . At the behest of the geometrical isomers produced by photoirradiation, the diversity encompasses an unprecedented eudesmane core and oxo-bridged hydroxy-olefin skeletons. Structure elucidation and the stereochemical outcome of the products are described via extensive NMR analysis. The present study serves as a model for tandem photoisomerization and transannular cyclization of natural products with enone/dienone functionality.Letter pubs.acs.org/OrgLett

Recent Developments in Transannular Reactions

“…Scheme 41 shows a similar transformation but employing a conjugate addition reaction to generate the nucleophilic enolate species. 65 In this particular case, the geometry of one of the alkenes present in the macrocyclic starting ketoepoxide had to be adjusted from trans to cis in order to be able to form the final transannular reaction product, which was accomplished by in situ photochemical isomerization. After this isomerization had taken place, the substrate underwent conjugate addition of water to the less hindered enone moiety, which was followed by the transannular ring-opening of the epoxide, the latter assisted by the presence of a Lewis acid catalyst.…”

Recent ring distortion reactions for diversifying complex natural products

“…8,9 A critical challenge in this area is to develop new strategies for the construction of high-quality libraries of molecules with many of the desirable features of natural products. [10][11][12] Current synthetic strategies including diversity-oriented synthesis (DOS), [13][14][15][16][17][18][19][20][21][22][23][24] biological-oriented synthesis (BiOS), 25,26 and function-oriented synthesis (FOS) [27][28][29][30][31][32][33][34] have been successfully applied in this eld. These strategies were categorized as a "bottom-up" approach.…”

Facile Detection of Light-Controlled Radical Scavengers from Natural Products Using In Situ UV-LED NMR Spectroscopy

“…Therefore, photoreactive molecules might be used as new bioactive materials. Recently, many light-responsive compounds have been discovered, such as cupriachelin, petrobactin, zerumbone oxide, and dicaffeoylquinic acids, and structural changes due to light irradiation have been elucidated [ 11 , 12 , 13 , 14 ]. We have been exploring photoreactive molecules as a way to expand structural diversity originating from nature and discover antioxidant molecules [ 15 , 16 ].…”