نتایج جستجو برای: Fiedel crafts cyclisation
تعداد نتایج: 2582 فیلتر نتایج به سال:
One-flow synthesis of tetrahydrocannabinol and cannabidiol using homo- and heterogeneous Lewis acids
Abstract Continuous flow chemistry holds great potential for the production of biologically relevant molecules. Herein, we present an approach continuous synthesis cannabidiol and tetrahydrocannabinol in a one-flow system. The designed route consists reaction cascade involving Friedel-Crafts alkylation, subsequent ring opening cyclisation up to 45% yield. reactions were successfully performed u...
(1R,5S)-2-Methyl-6,7-benzomorphan has been synthesised from (R)-(benzyloxy)(phenyl)acetaldehyde. On a 2-mmol scale Bi (OTf)3 promoted Aza-Prins reaction with N-tosylhomoallylamine afforded an 88/12 mixture of 6-oxa-2-azabicyclo[3.2.1]octanes. Major diastereoisomer was converted to enantiomerically pure (2S,4S)-2-benzyl-1- methylpiperidin-4-ol via high-yielding sequence hydrogenolysis/N-detosyla...
The synthesis of 1,5-dihydroxy-9,10-anthraquinone (17); (1,5-DHA) was accomplished during, attempts towards the synthesis one of its derivatives called anthralin (1,8-dihydroxy-9-anthrone) which is known as an antipsoriasis drug since 1916 [1]. This work is a new reigiospecilic preparation of 1,5-DHA based on Friedel-Crafts reaction starting from 1,4-dimethoxybenzene. This synthetic route, ...
The oxidative cyclisation reactions of 2’-hydroxychalcones to corresponding aurones and flavones are discussed. While Hg2+, Cu2+ and Tl3+-mediated oxidative cyclisation of 2’-hydroxychalcones selectively give aurones, I2, Se4+, In3+, Cu+ and Fe3+-mediated reactions preferable give flavones. The general mechanisms of these oxidative cyclisation reactions are proposed.
The study of Pd-catalysed cyclisation reactions of alkenols using different catalytic systems is reported. These transformations affect the stereoselective construction of mono- and/or bicyclic oxaheterocyclic derivatives depending on a starting alkenol. The substrate scope and proposed mechanism of Pd-catalysed cyclisation reactions are also discussed. Moreover, the diastereoselective Pd-catal...
Fiedel and Haynes misrepresent many of the arguments we have made concerning the overkill hypothesis. We clarify some of these mischaracterizations and call attention to some of the factual and logical errors in their paper. 2003 Elsevier Ltd. All rights reserved.
Cascade radical cyclisation involving homolytic aromatic substitution has been used to synthesise new tetracycles. Treatment of vinyl iodide radical precursors with Me(3)Sn. radicals (from hexamethylditin) yielded intermediate vinyl radicals which undergo 5-exo cyclisation onto suitably placed nitrile groups to yield intermediate iminyl radicals. The iminyl radicals undergo aromatic homolytic s...
A novel osmium-catalysed oxidative cyclisation of 1,2-diols bearing a pendant vinyl silane affords THFs that contain silicon functionality at the ring junction. When the cyclisation occurs onto a vinyl benzyldimethylsilyl group, the resulting silyl group can act as a masked hydroxyl group and undergo a Fleming-Tamao type oxidation at a later stage to form the corresponding lactol. The scope of ...
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