Synthetic Route to 4, 4a‐ and 3, 4‐Dihydroxanthones through [4+2] Cycloaddition and Base‐Assisted Sigmatropic Rearrangement. Issue 19 (24th May 2017)

• Record Type: Journal Article
• Authors: Chernov, Nikita M.; Shutov, Roman V.; Sharoyko, Vladimir V.; Kuz'mich, Nikolay N.; Belyakov, Alexander V.; Yakovlev, Igor P.
• Is Part Of: European journal of organic chemistry. Issue 19(2017)
• Page Start: 2836
• Page End: 2841
• Publication Date: 2017-05-24
• Subjects: Cycloaddition -- Cytotoxicity -- Fused ring systems -- Isomerization -- Sigmatropic rearrangement; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201700310
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract : The [4+2] cycloaddition of chromone‐fused dienes with enamines was found to be an efficient method for the synthesis of 4, 4a‐ and 3, 4‐dihydroxanthone derivatives. Either product type could be obtained by choosing the proper conditions [reaction time and addition of La(NO3 )3 as a Lewis acid]. Calculations using density functional theory and Møller–Plesset perturbation theory showed that the isomerization of 4, 4a‐dihydroxanthones to 3, 4‐dihydroxanthones occurred through a base‐assisted sigmatropic rearrangement. The described reaction provides a convenient route to a natural‐product‐inspired group of 4, 4a‐dihydroxanthones with cytotoxic activity. Abstract : 4, 4a‐Dihydroxanthone derivatives with cytotoxic activity are easily accessible by the cycloaddition of chromone‐fused dienes with enamines. They can undergo further isomerization to 3, 4‐dihydroxanthones through a base‐assisted sigmatropic rearrangement that is promoted by lanthanum salts.