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Showing 1 to 10 of 10 for “"chromenes"”.
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Some chemistry of chromenes and chromanones
… chroman-4-ols yielded the corresponding chromenes. The established synthesis of chromenes involving the rearrangement of aryl propargyl ethers has been modified such that the chromene can be prepared directly by reaction of an alkynol with a suitably activated phenol at an alumina …
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Shedding Light on Phytochemical Diversity: Photochromism of chromenes isolated from Piper kelleyi
… the photochromic behavior of naturally occurring chromenes and its role in the biosynthesis of a variety of natural product architectures. Ultimately, chromenes and ortho-quinonemethide derived natural products will be used to understand their role in anti-herbivore activity by exploring the …
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Some chemistry of bromobenzopyrans
… of the resulting chroman-4-ols gave the 2H-chromenes in excellent yield. Addition of N-bromosuccinimide in moist dimethyl sulfoxide to the 2H-chromenes gave the trans-3-bromochroman-4-ols in good yield. Subsequent dehydration using a catalytic amount of 4-toluenesulfonic acid in refluxing …
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Studies in Benzopyran chemistry
… 7-bromo-, 8-bromo- and 6,8-dibromo- 2,2-dimethylchromenes have been synthesised. The 6-bromoand 8-bromo-derivatives were prepared by Claisen rearrangement of aryl propargyl ethers, derived from phenols and 3-chloro-3-methylbut-1-yne. 7-Bromo- and 6,8-dibromo-2,2-dimethylchromenes were obtained by …
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RECENT ADVANCES IN IMINIUM SALT CATALYSED ASYMMETRIC EPOXIDATION
… up to 98% ee in the epoxidation of racemic cis-chromenes. The second part of chapter two details the first known examples of asymmetric epoxidation upon nitrogen-protected dihydroquinoline substrates, affording enantioselectivities as high as 73% ee. In both parts of chapter two, non-aqueous …
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The application of organocatalytic Asymmetric Epoxidation
… has been successfully employed to access chiral chromenes within the Page group. Iminium-catalysed asymmetric epoxidation methodology has been applied to the synthesis of levcromakalim, 3 trans-khellactone, and lomatin,4 which are based on a chromene-type structure. In this thesis, we offer a …
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Rhodium-catalyzed Asymmetric Carbon-Carbon Bond Formation Leading to the Development of Rhodium/Palladium Multi-metal Catalysis
… the reaction scope, including the synthesis of chromenes. Chapter 3 describes the importance of time resolution and ligand interference in the development of enantioselective domino rhodium/palladium catalysis employing chiral and achiral ligands. The development of this method provided access …
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Switching hybrid polymers with physically and covalently entrapped organic photochromes
… incorporation of photochromic spirooxazines and chromenes. The development and optimisation of work was performed via two different routes (dye and matrix ones), that led to photochromic multi-layer coating systems with coloration depth and photostabilities comparable to commercially available …
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Glioma: A Tale of Corticosteroids, Thiopurines and Proposed Novel AntiGlioma Small Molecules
… molecules; tetrahydroisoquinoline (THIQ) and chromenes. These molecules were screened in vitro to find the most potent anticancer derivatives that exhibited the least toxicity on normal stromal cells. EDL-360 (5-10 µM) and SP-6-27 (IC50 = 7-21 nM) were the most potent analogs of THIQ and …
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Activación carbolífica de enlaces múltiples carbono-carbono: Reacciones de migración de ésteres propargílicos promovidas por IPyxBF4 y de cicloadición intermolecular catalizadas por complejos de oro (I)
… the regio- and diastereoselective synthesis of chromenes. In this transformation, the alkyne-gold(I) complex reacts with the alkene to generate an intermediate that evolves via intramolecular Friedel-Crafts cyclization.