9 research outputs found
Six-membered ring systems: with O and/or S atoms
A large variety of publications involving O- and S-6-membered ring systems
have appeared in 2017. The importance of these heterocyclic compounds
is highlighted by the huge number of publications on the total
synthesis of natural oxygen derivatives and of other communications
dedicated to synthetic derivatives.
Reviews on stereoselective organocatalytic synthesis of tetrahydropyrans
(17EJO4666), of tetrahydropyrans and their application in total synthesis of
natural products (17CSR1661), on the synthesis of the less thermodynamically
stable 2,6-trans-tetrahydropyrans (17S4899), on enantioselective
synthesis of polyfunctionalized pyran and chromene derivatives
(17TA1462), and on enantioselective and racemic total synthesis of
camptothecins, including the formation of their pyran-2-one ring
(17SL1134), have appeared.
Advances in the transition metal-catalyzed synthesis of pyran-2/4-ones
(17TL263), N-heterocyclic carbene (NHC)-catalyzed achiral synthesis of
pyran-2-one, coumarin and (thio)chromone derivatives (17OBC4731), on
the synthesis and transformation of 2H-pyran-2-ones (17T2529) and
2-styrylchromones (17EJO3115) into other heterocyclic compounds, have
been surveyed. The strategies to build up the tetrahydropyranyl core of
brevisamide (17H(95)81) and the reactions of ketyl radicals, generated from
carbonyl derivatives under transition-metal photoredox-catalyzed conditions,
leading to isochromen- and chroman-type compounds (17CC13093) were
disclosed. Developments in the synthesis of pentafluorosulfanyl(chromene
and coumarin) derivatives (17TL4803), photoswitchable D9-tetrahydrocannabinol
derivatives (17JA18206), and aminobenzopyranoxanthenes
with nitrogen-containing rings (17JOC13626) have been studied.info:eu-repo/semantics/publishedVersio
Neighboring carbonyl group assisted hydration of unsymmetrical aryl alkynes overriding regular selectivity
A mild and highly regioselective gold-catalyzed hydration of Îł-acetoxy aryl alkynes leading to anti-Markovnikov products by the assistance of a neighboring carbonyl group is presented. The reaction procedure operates under room temperature conditions with broad functional group tolerance in presence of more than stoichiometric amount of water to access two different types of acyloins in good to excellent yields. Acetate protected acyloins were produced from primary and secondary substrates, while tertiary ones react differently to give free-acyloins under identical conditions. The mechanistic pathways for such divergent functionalization were deduced from isotopic mechanistic results
Gold(I)-Catalyzed Cyclization for the Synthesis of 8âHydroxy-3- substituted Isocoumarins: Total Synthesis of Exserolide F
A highly
regioselective goldÂ(I)-catalyzed 6-<i>endo-dig</i> cyclization
of 2,2-dimethyl-5-(alkynyl)-4<i>H</i>-benzoÂ[<i>d</i>]Â[1,3]Âdioxin-4-ones for the synthesis of 8-hydroxy-3-substituted
isocoumarins is described. Key features of the reaction include the
broad substrate scope, scalability, and tolerance for protecting groups.
The synthetic utility of this novel method is demonstrated by the
first total synthesis of exserolide F, an isocoumarin-containing polyol
natural product
Synthesis of azulene-substituted benzofurans and isocoumarins via
First published: 08 Dec 2017The preparation of azulene-substituted benzofurans and isocoumarins was established by two types of intramolecular cyclization reaction of 1-ethynylazulenes. 2-(1-Azulenyl)- and 2,3-bis(1-azulenyl)benzofurans were prepared by the palladium-catalyzed cross-coupling reaction of 1-iodoazulenes with 2-ethynylphenol and that of 1-ethynylazulenes with 2-iodophenol under Sonogashira-Hagihara reaction conditions following the intramolecular nucleophilic addition of the oxygen nucleophile to the presumed 1-arylethynylazulenes. In contrast, 1-(phenylethynyl)azulenes bearing an o-methoxycarbonyl function on the substituted phenyl moiety exhibited intramolecular cyclization either in the presence of trifluoroacetic acid or N-iodosuccinimide (NIS) to afford azulene-substituted isocoumarins and 4-iodoisocoumarins, and the structures were clarified by single-crystal X-ray analysis. The optical properties of these compounds were also investigated by UV/vis spectroscopy and theoretical calculations.ArticleORGANIC & BIOMOLECULAR CHEMISTRY. 16(3):480-489 (2018)journal articl