Showing papers on "Glycal published in 2016"
TL;DR: A primary kinetic isotope effect is observed, which indisputably indicates that the proposed deprotonation occurs during the isomerization of U to Ψ and establishes the mechanism followed by the Ψ synthases.
Abstract: The pseudouridine synthases isomerize (U) in RNA to pseudouridine (Ψ), and the mechanism that they follow has long been a question of interest. The recent elucidation of a product of the mechanistic probe 5-fluorouridine that had been epimerized to the arabino isomer suggested that the Ψ synthases might operate through a glycal intermediate formed by deprotonation of C2′. When that position in substrate U is deuterated, a primary kinetic isotope effect is observed, which indisputably indicates that the proposed deprotonation occurs during the isomerization of U to Ψ and establishes the mechanism followed by the Ψ synthases.
35 citations
TL;DR: In this study, glycal formation was efficiently prevented by deprotonating the hydroxyl group in position 2 of the glyconitriles during the process.
Abstract: A new strategy for the synthesis of acyl β-C-glycosides is described. The reactivity of glyconitriles toward organometallic reagents such as organomagnesium or organolithium derivatives was studied, affording acyl β-C-glycosides in moderate to good yields. In this study, glycal formation was efficiently prevented by deprotonating the hydroxyl group in position 2 of the glyconitriles during the process.
24 citations
TL;DR: This protocol has been expanded to include glycal substrates, which undergo a one-pot alkynylation-Ferrier reaction to produce functionalized sugars in moderate to excellent yields with high diastereoselectivity.
23 citations
TL;DR: A one-pot cyclization sequence involving the Ferrier and Povarov-like reactions in the synthesis of novel pentacyclic N-heterocycles: benzopyran-fused pyranoquinolines is reported.
Abstract: The Ferrier rearrangement and the Povarov reaction have proven indispensable tools in carbohydrate chemistry and the synthesis of N-heterocycles, respectively. We hereby report a one-pot cyclization sequence involving the Ferrier and Povarov-like reactions in the synthesis of novel pentacyclic N-heterocycles: benzopyran-fused pyranoquinolines. The reaction entails three component condensation of a glycal with a variety of anilines and 2-hydroxybenzaldehydes under Lewis acid catalysis to yield the title compounds in 4–24 hours of reaction time, in moderate to high yields and excellent diastereoselectivity. Of the Lewis acid catalysts deployed [Sc(OTf)3, Al(OTf)3, Cu(OTf)2, CuOTf, I2, InCl3, and La(OTf)3] in various solvents (acetonitrile, THF, dichloromethane, 1,2-dichloroethane and diethyl ether) at room and elevated temperatures, Sc(OTf)3 (10 mol%) in acetonitrile at 70 °C gave the best results, with excellent diastereoselectivity. CAN-mediated oxidative ring opening of the pentacyclic N-heterocycle gave the corresponding enantiometrically pure chromenoquinoline bearing a pendant sugar moiety.
16 citations
TL;DR: The synthesis involves an anomeric O-alkylation for the synthesis of 2-deoxy β-linked disaccharide, a tert-butyldimethylsilyl triflate-catalyzed α-selective L-rhodinosylation, and a lithium 4,4'-di-tert-butylbiphenyl-mediated reductive debenzylation and concomitant reductive lithiation-elimination.
7 citations
4 citations
TL;DR: A regio- and stereo-controlled, rhodium(II)-catalyzed amidoglycosylation of alcohols has been developed using O-acetylated glycals, trichloroethoxysulfonamide, and iodosobenzene to afford the β-O-glycosides with acceptable yields up to 84%.
2 citations
19 Apr 2016
2 citations
TL;DR: In this paper, a new strategy for the synthesis of acyl β-C-glycosides is described, which deprotonates the hydroxyl group in position 2 of the glyconitriles during the process.
Abstract: A new strategy for the synthesis of acyl β-C-glycosides is described. The reactivity of glyconitriles toward organometallic reagents such as organomagnesium or organolithium derivatives was studied, affording acyl β-C-glycosides in moderate to good yields. In this study, glycal formation was efficiently prevented by deprotonating the hydroxyl group in position 2 of the glyconitriles during the process.
1 citations
TL;DR: In this paper, a one-pot cyclization sequence involving the Ferrier and Povarov-like reactions in the synthesis of novel pentacyclic N-heterocycles: benzopyran-fused pyranoquinolines.
Abstract: The Ferrier rearrangement and the Povarov reaction have proven indispensable tools in carbohydrate chemistry and the synthesis of N-heterocycles, respectively. We hereby report a one-pot cyclization sequence involving the Ferrier and Povarov-like reactions in the synthesis of novel pentacyclic N-heterocycles: benzopyran-fused pyranoquinolines. The reaction entails three component condensation of a glycal with a variety of anilines and 2-hydroxybenzaldehydes under Lewis acid catalysis to yield the title compounds in 4–24 hours of reaction time, in moderate to high yields and excellent diastereoselectivity. Of the Lewis acid catalysts deployed [Sc(OTf)3, Al(OTf)3, Cu(OTf)2, CuOTf, I2, InCl3, and La(OTf)3] in various solvents (acetonitrile, THF, dichloromethane, 1,2-dichloroethane and diethyl ether) at room and elevated temperatures, Sc(OTf)3 (10 mol%) in acetonitrile at 70 °C gave the best results, with excellent diastereoselectivity. CAN-mediated oxidative ring opening of the pentacyclic N-heterocycle gave the corresponding enantiometrically pure chromenoquinoline bearing a pendant sugar moiety.
1 citations
TL;DR: In this paper, N-alkylated tetrahydropyrano[3,2-c ]quinolines were synthesized via intramolecular Friedel-Crafts alkylation using a 1- O -acetylglucosyl derivative as the key intermediate.
Abstract: Diastereoselective synthesis of novel and enantiopure N-alkylated tetrahydropyrano[3,2- c ]quinolines is described via intramolecular Friedel–Crafts alkylation using a 1- O -acetylglucosyl derivative as the key intermediate. Unprecedented formation of new glycal derivatives and α,β-unsaturated carbaldehyde products is also discussed.