Showing papers on "Glycal published in 1991"
143 citations
84 citations
75 citations
TL;DR: A short and straightforward route has been accomplished for the synthesis of C-2-formyl glycals by a Vilsmeier-Haack reaction of glycals.
52 citations
TL;DR: The glycosylation with the N-acetylneuraminic acid (Neu5Ac) donor 1 of the 6-OH position of D-galactose in various nitriles promoted by methylsulfenyl triflate at different temperatures is reported.
51 citations
TL;DR: In this paper, a novel approach to the synthesis of glycosides and disaccharides of ketofuranoses and ketopyranoses by epoxidation of exocyclic glycals and reaction of the intermediate epoxides with different alcohols is described.
41 citations
TL;DR: In this paper, an enzyme-catalyzed preparation of β-2-deoxy-D-glucosides and galactosides including disaccharides has been achieved using the corresponding glycals as substrates.
35 citations
33 citations
TL;DR: Nucleoside 2-deoxyribosyltransferase is found to catalyze the hydration of D-ribal in the absence of nucleic acid bases and the synthesis of deoxyribonucleosides from ribal in their presence, affording a new method for the preparation of 2'-deoxy Ribon nucleosides.
Abstract: In the absence of acceptors nucleoside 2-deoxyribosyltransferase catalyzes the slow hydrolysis of 2'-deoxynucleosides. During this hydrolytic reaction, D-ribal (1,4-anhydro-2-deoxy-D-erythro-pent-1-enitol), a glycal of ribose hitherto encountered only as a reagent in organic synthesis, is generated spontaneously, disappearing later as 2'-deoxynucleoside hydrolysis approaches completion. Nucleoside 2-deoxyribosyltransferase is found to catalyze the hydration of D-ribal in the absence of nucleic acid bases and the synthesis of deoxyribonucleosides from ribal in their presence, affording a new method for the preparation of 2'-deoxyribonucleosides. The stereochemistry of nucleoside formation from ribal supports the intervention of deoxyribosyl-enzyme intermediate. The equilibrium constant for the covalent hydration of ribal is found to be approximately 65.
30 citations
TL;DR: In this paper, enol-type alkenes, such as 2,3-dimethylbenzodioxin (1), O-tetrabenzyl glycal (3), 1,2-bis(trimethylsilyloxy)cycloalkenes (9) were transformed in excellent yields to their labile epoxides by dimethyldioxirane (as acetone solution).
27 citations
TL;DR: In this paper, a treatment of glycopyranosyl phenyl sulfoxides 2ah, 1, 2bh, 1 with two equivalents of lithium diisopropylamide provides directly the C-2-lithiated glycal intermediates 3aAh, 1.
TL;DR: The 3-thio-glycals were successfully employed for the synthesis of 3′-mercapto-3′-deamino-doxorubicin and its analogues as mentioned in this paper.
TL;DR: Spectroscopic methods unambiguously showed that alpha-D-C-linked disaccharides had been formed.
TL;DR: Treatment of tri-O-acetyl-D-glycals with metal chlorides in acetic anhydride afforded the C-3 epimer of the glycal Triacetate with pseudo-glycal triacetate and unreacted glycaltriacetate as an equilibrium mixture.
Abstract: Treatment of tri-O-acetyl-D-glycals, e.g., tri-O-acetyl-D-glucal, tri-O-acetyl-D-allal and tri-O-acetyl-D-galactal, with metal chlorides in acetic anhydride afforded the C-3 epimer of the glycal triacetate with pseudo-glycal triacetate and unreacted glycal triacetate as an equilibrium mixture. The C-3 epimer of the glycal was readily separated from the reaction mixture using preparative HPLC.
TL;DR: In this paper, Protected 3-azido-2,3-dideoxy-arabino-furanose was prepared by 1,4-addition of hydrazoic acid to disilylated α,β-unsaturated aldehyde followed by acetylation.
Abstract: α,β-Unsaturated aldehyde prepared from tri-O-acetyl-D-glucal was acetalated and benzoylated to give α,β-unsaturated acetal . Hydrogenation of the double bond followed by methanolysis resulted in methyl 2,3-dideoxyfuranosyl glycoside which was used for nucleoside coupling with silylated N 6 -isobutyrylcytosine and silylated thymine. Protected 3-azido-2,3-dideoxy-arabino-furanose was prepared by 1,4-addition of hydrazoic acid to disilylated α,β-unsaturated aldehyde followed by acetylation
TL;DR: In this article, the title synthesis was described by 1,2-addition of 20mercaptpyridine on simple (2 and 3 ) as well as on sensitive glycal saccharides (7 and 8 ) to obtain the respective 2-deoxy 2-pyridyl 1-thioglycopyranosyl donors.
TL;DR: In this paper, it was demonstrated that the observed selectivity on the -4 position cannot be explained by acetyl migration during the reaction, and that the effect of hydrazine acetate on deacetylation on peracetylated glycals like D-xylal, D-glucal and L-rhamnal was investigated.
TL;DR: In this article, it was shown that 4,6-O-benzylidene-1,2-dideoxy-3-C-(2-propenyl- or 2-methyl)-D-lyxo-hex-1-enopyranose gave the corresponding ribo isomer in a ratio ranging from 1 : 1 to 10 : 1
Abstract: 4,6-O-Benzylidene-1,2-dideoxy-D-threo-hex-1-enopyranose-3-urose reacted with allylic organometallic reagents, CH2=CR–CH2–Metal [R = H or CH3; Metal = MgCl, AlEt2, or Ti(OPri)3], to selectively give 4,6-O-benzylidene-1,2-dideoxy-3-C-(2-propenyl- or 2-methyl-2-propenyl)-D-lyxo-hex-1-enopyranose. On the other hand, the erythro isomer gave 3-C-(2-propenyl- or 2-methyl-2-propenyl)-D-arabino-hex-1-enopyranose and the corresponding ribo isomer in a ratio ranging from 1 : 1 to 10 : 1
01 Jan 1991
TL;DR: In this article, three different reactions were selectively observed at the anomeric centre of appropriate glucopyranosyl derivatives when treated with samarium iodide(II): formation of glucal, reductive desulfonylation and formation of C-glycosides upon addition of cyclopentanone.
Abstract: Three different reactions were selectively observed at the anomeric centre of appropriate glucopyranosyl derivatives when treated with samarium iodide(II):formation of glucal,reductive desulfonylation and formation of C-glycosides upon addition of cyclopentanone