A new ferrier system: 2-C-acetoxymethylglycals. A covenient entry to 2-C-methylene glycosides
01 Jan 1993-Journal of The Chemical Society, Chemical Communications (The Royal Society of Chemistry)-Iss: 18, pp 1394-1395
TL;DR: In this paper, the synthesis of tri-O-benzyl-2-C-acetoxymethyl glycals and subsequent Ferrier rearangement to give 2C-methylene glycosides is described.
Abstract: Syntheis of tri-O-benzyl-2-C-acetoxymethylglycals and subsequent Ferrier rearangement to give 2-C-methylene glycosides is described.
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TL;DR: A review of recent developments in the use of promoters for the Ferrier rearrangement of O-, N-, C- and S-nucleophiles with glycals can be found in this paper.
121 citations
TL;DR: An efficient approach for the synthesis of a variety of C-aryl and spiro-C-aryl glycosides is described, which relies on a sequential enyne metathesis to generate the 1,3-diene moiety and Diels-Alder reaction with different dienophiles followed by aromatisation.
Abstract: An efficient approach for the synthesis of a variety of C-aryl and spiro-C-aryl glycosides is described. This diversity-oriented strategy employed here relies on a sequential enyne metathesis to generate the 1,3-diene moiety and Diels–Alder reaction with different dienophiles followed by aromatisation. Whereas cross-enyne metathesis with ethylene gas is used to install the 1,3-diene moiety at the anomeric centre for the synthesis of C-aryl glycosides, an intramolecular enyne metathesis on the sugar enyne is performed to generate the 1,3-diene moiety for the synthesis of spiro-C-aryl glycosides. Efforts to extend this strategy to the synthesis of the core structure of natural C-aryl glycoside gilvocarcin are also described. A combination of both C-aryl and spiro-C-aryl glycosides in the same moiety to combine the features thereof has also been accomplished. A tandem enyne metathesis/Diels–Alder reaction/aromatisation has also been attempted to directly access the C-aryl glycosides in one pot albeit in low yield.
56 citations
TL;DR: The conversion of cyclopropane-fused carbohydrates into oxepines is an attractive method for accessing diverse members of the septanoside family of carbohydrate mimetics, and 2-Bromooxepines are obtained through silver(I)-promoted thermal ring expansion of a d-glucal-derived gem-dihalocyclopropanated sugar.
Abstract: The conversion of cyclopropane-fused carbohydrates into oxepines is an attractive method for accessing diverse members of the septanoside family of carbohydrate mimetics. 2-Bromooxepines are obtained through silver(I)-promoted thermal ring expansion of a d-glucal-derived gem-dihalocyclopropanated sugar. In contrast, cyclopropane ring cleavage under basic conditions leads to 2-C-branched pyranosides, not the 2-bromooxepine structures assigned in an earlier report.
49 citations
TL;DR: In this article, a new class of 2-C-formyl glycals, incorporating an α,β-unsaturated carbonyl system, have been proposed as potential synthons for numerous organic transformations.
44 citations
TL;DR: In this paper, C-2-Methylene O- and C-glycosides are readily synthesized from C-acetoxymethyl glycals using Nafion-H®, montmorillonite K-10, LiClO4 (0.07m) in dichloromethane and Pd(PPh3)4 as catalysts.
38 citations
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TL;DR: DMDC as well as 2'-deoxy-2'-methylidene-5-fluorocytidine (19a) showed potent antileukemic activity against murine L 1210 cells in culture and in vivo antitumor activity of DMDC against L1210 was also described.
Abstract: A new type of antineoplastic nucleoside, 2'-deoxy-2'-methylidenecytidine (DMDC) has been synthesized from the corresponding 2'-keto pyrimidine nucleosides 3 and 8 by the Wittig reaction. During the course of the reaction, we found that an intermediate betaine could pick a proton from the excess triphenylphosphonium bromide to form the 2'-phosphonium salts 5 and 10, which could be further converted into the 2'-deoxy-2'-methylidene nucleosides 4 and 9 by treatment with sodium hydride. Various 5-substituted DMDC derivatives 19a-e,h and their uracil congeners 16a-h were also synthesized from the corresponding 5-substituted uridines 12a-f,h. Among them, DMDC as well as 2'-deoxy-2'-methylidene-5-fluorocytidine (19a) showed potent antileukemic activity against murine L1210 cells in culture. The activity of DMDC and 19a toward various human tumor cells in culture compared with 1-beta-D-arabinofuranosylcytosine and 5-fluorouracil was also examined. In vivo antitumor activity of DMDC against L1210 was also described.
88 citations
TL;DR: In this article, Stannic chloride-catalysis was used for rearrangement of 3,4,6-tri-O -acetyl-1,5-anhydro-2-deoxy-d -hex-l-enitol.
77 citations
TL;DR: In this paper, the mechanisms of these reactions are discussed and a high degree of stereospecificity is obtained for dimeric 1,2-cis-2,deoxy-2-nitroso-α-D-aldopyranosyl chlorides.
Abstract: Reaction of nitrosyl chloride with acetylated glycals affords, with a high degree of stereospecificity, dimeric acetylated 1,2-cis-2-deoxy-2-nitroso-α-D-aldopyranosyl chlorides. Reaction of acetylated glycals with dinitrogen tetroxide, depending on the reaction conditions, can give either acetylated 2-deoxy-2-nitroso-α-D-aldopyranosyl nitrates as dimers or acetylated 2-nitroglycals. The mechanisms of these reactions are discussed.
53 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
50 citations