81668-63-5Relevant articles and documents
Insight into the Ferrier Rearrangement by Combining Flash Chemistry and Superacids
Bhuma, Naresh,Lebedel, Ludivine,Yamashita, Hiroki,Shimizu, Yutaka,Abada, Zahra,Ardá, Ana,Désiré, Jér?me,Michelet, Bastien,Martin-Mingot, Agnès,Abou-Hassan, Ali,Takumi, Masahiro,Marrot, Jér?me,Jiménez-Barbero, Jesús,Nagaki, Aiichiro,Blériot, Yves,Thibaudeau, Sébastien
supporting information, p. 2036 - 2041 (2020/11/30)
The transformation of glycals into 2,3-unsaturated glycosyl derivatives, reported by Ferrier in 1962, is supposed to involve an α,β unsaturated glycosyl cation, an elusive ionic species that has still to be observed experimentally. Herein, while combination of TfOH and flow conditions failed to observe this ionic species, its extended lifetime in superacid solutions allowed its characterization by NMR-based structural analysis supported by DFT calculations. This allyloxycarbenium ion was further exploited in the Ferrier rearrangement to afford unsaturated nitrogen-containing C-aryl glycosides and C-alkyl glycosides under superacid and flow conditions, respectively.
Yb(OTf)3-catalyzed C-glycosylation: Highly stereoselective synthesis of C-pseudoglycals
Takhi, Mohamed,Abdel Rahman, Adel A.-H.,Schmidt, Richard R.
, p. 4053 - 4056 (2007/10/03)
A variety of functionalized C-pseudoglycals (pseudoglycal C-glycosides or C-hex-2-enopyranosides) have been obtained in excellent yields and stereoselectivity from the Yb(OTf)3-catalyzed reaction of tri-O-acetyl glucal with silylated nucleophil
Molybdenum-catalyzed allylic substitution in glycals: A C-C bond-forming Ferrier-type reaction
Malkov, Andrei V.,Farn, Benjamin P.,Hussain, Nigel,Kocovsky, Pavel
, p. 1735 - 1745 (2007/10/03)
The mild, Lewis-acidic complexes [Mo(CO)4Br2]2, (MeCN)2Mo(CO)3(SnCl3)Cl, and (acac)2Mo(OTf)2 have been found to catalyze the C(1)-specific C-glycosylation reaction of glycal acetates 1-3 with silyl enol ethers 4a-4c and electron-rich aromatics 5a, 5b (PhOMe, PhOH). While silyl enol ethers produce predominantly α-C-glycopyranosides (with 2 : 1 to 4 : 1 selectivity), aromatics tend to afford mainly β-C-glycopyranosides (2 : 1 to 3 : 1) in a thermodynamically controlled process.
Syntheses and reactions of saturated and 2,3-unsaturated vinyl and 1'-substituted-vinyl glycosides
De Raadt,Ferrier
, p. 93 - 107 (2007/10/02)
Reaction of tetra-O-acetyl-α-D-glucopyranosyl bromide with bis(acylmethyl)mercurys [Hg(CH2COR)2] afforded acetylated vinyl [by use of bis(formylmethyl)mercury] or 1'-substituted-vinyl β-D-glucopyranosides 11-13 in high yields. When used together with phenyl 4,6-di-O-acetyl-2,3-dideoxy-1-thio-α-D-erythro-hex-2-enopyranoside, these reagents gave analogous vinyl 4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranosides 20-23 which, on treatment with Lewis acids, isomerised to the corresponding C-glycosyl compounds, i.e., (4,6-di-O-acetyl-2,3-dideoxy-D-ertyrho-hex-2-enopyranosyl)acetaldehyd e (24,25) or the corresponding glycosylated methyl ketones 26, 27. A new route to C-3-branched glycals involves treatment of the above thioglycoside or the unsaturated vinyl glycosides with bis(benzoylmethyl)-mercury. Reaction of tetra-O-acetyl-α-D-glucopyranosyl bromide with bis(acylmethyl)mercurys [Hg (CH2COR)2] afforded acetylated vinyl [by use of bis(formylmethyl)mercury] or 1′-substituted-vinyl β-D-glucopyranosides 11-13 in high yields. When used together with phenyl 4 ,6-di-O-acetyl-2,3-dideoxy -1-thio-α-D-erythro -hex-2-enopyranoside, these reagents gave analogous vinyl 4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranosides 20-23 which, on treatment with Lewis acids, isomerised to the corresponding C-glycosyl compounds, i.e., (4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranosyl) acetaldehyde (24,25) or the corresponding glycosylated methyl ketones 26, 27. A new route to C-3-branched glycals involves treatment of the above thioglycoside or the unsaturated vinyl glycosides with bis(benzoylmethyl)-mercury.
Stereocontrolled Routes to Functionalized C-Glycopyranosides
Dawe, Robert David,Fraser-Reid, Bert
, p. 522 - 528 (2007/10/02)
4,6-O-Ethylidene-D-glucopyranose (1) reacts with an acid-washed, stabilized Wittig reagent to give the trans-oct-2-enoate 2 in excellent yield.Cyclization is effected by treatment with dilute base, and after 1 h, a 1:1 mixture of anomers exists which is the optimum concentration of the α-D form.Continuing base treatment for 5 h leads to the β-D anomer exclusively. α-D-C-Glycopyranosides can be obtained as predominant products by Lewis acid catalyzed condensation of acetylated glycals with siloxyalkenes, and anomerization to the β-D forms can be effected with potassium tert-butoxide.For a given pair of these anomers, 1H or 13C NMR pa rameters can be used for assigning configuration α or β.
α-C-Glycopyranosides from Lewis Acid Catalysed Condensations of Acetylated Glycals and Enol Silanes
Dawe, Robert David,Fraser-Reid, Bert
, p. 1180 - 1181 (2007/10/02)
Acetylated glycals undergo Lewis acid-catalysed condensations with enol silanes in virtually quantitative yields to form C-glycopyranosides in which the thermodynamically unfavourable α-'anomers' are formed predominantly.
