71978-99-9Relevant academic research and scientific papers
13C NMR analysis of 3,6-dihydro-2 H -pyrans: Assignment of remote stereochemistry using axial shielding effects
Bartlett, Mark J.,Northcote, Peter T.,Lein, Matthias,Harvey, Joanne E.
, p. 5521 - 5532 (2014/07/08)
The rational analysis of 13C NMR axial shielding effects has enabled the assignment of remote relative stereochemistry in 3,6-oxygen-substituted 3,6-dihydro-2H-pyrans. Comparison of the 13C NMR shifts of equivalent centers in cis- an
The use of ultrastable y zeolites in the Ferrier rearrangement of acetylated and benzylated glycals
Levecque, Pieter,Gammon, David W.,Jacobs, Pierre,De Vos, Dirk,Sels, Bert
experimental part, p. 828 - 835 (2010/09/08)
The Ferrier rearrangement of a selection of protected glycals was successfully performed using a commercially available H-USY zeolite CBV-720 as catalyst, selected after screening a range of similar catalysts. By incorporating either alcohols, thiophenol, trimethylsilyl azide or allyltrimethylsilane in the reaction it was shown that a range of O-, S-, N- and C-glycosides could be formed. With benzylated glucal and galactal in particular, use of the CBV-720 catalyst led to significantly higher yields of the 2,3-dehydroglycosides than previously reported.
Steric constraints against [3,3]-sigmatropic rearrangement of allylic azides. A convenient approach to β-L-4-aminopent-2-enoglyceropyranosides
Fava, Cristiana,Galeazzi, Roberta,Mobbili, Giovanna,Orena, Mario
, p. 2731 - 2741 (2007/10/03)
Starting from alkyl α-D-4-0-methanesulphonylpent-2-enoglyceropyranosides 13a-c, nucleophilic substitution carried out with polymer-supported azide ion led to regioisomeric mixtures of the azides 14a-c and 15a-c. An analogous result, due to a [3,3]-sigmatr
Palladium - Cobalt-mediated double annulation Process: A new strategy to chiral and polysubstituted bis-cyclopentanoids on carbohydrate precursors
Naz, Noshena,Al-Tel, Taleb H.,Al-Abed, Yousef,Voelter, Wolfgang,Ficker, Robert,Hiller, Wolfgang
, p. 3250 - 3255 (2007/10/03)
The iodohydrins 2, 4, and 5 were prepared by the ring opening of benzyl 2-O-p-tosyl-3,4-anhydro-β-L-arabinopyranoside (1) or benzyl 2,3-anhydro-4-O-acetyl-α-D-ribopyranoside (3), respectively, using sodium acetate, sodium iodide, and acetic acid in acetone which on treatment with POCl3 in pyridine yielded the unsaturated sugars 6 and 7. After deacetylation of 7 with MeOH/H2O/Et3N (3:2:1) and treatment of 8 with tosyl chloride/pyridine at 50°C 9 was obtained. The reaction of benzyl 2-O-p-tosyl-3,4-dideoxy-α-D-glycero-pent-3-enopyranoside (6) and benzyl 2,3,4-trideoxy-4-chloro-β-L-glycero-pent-2-enopyranoside (9) with the sodium enolate of dimethyl propargylmalonate in the presence of catalytic amounts of tetrakis(triphenylphosphine)palladium(0) afforded the branched-chain sugars 10 and 11. The isomer 10 was obtained as a minor product from 6 with retention of configuration around C-2, and the major isomer 11 as a result of allylic rearrangement in a ratio of 1:9. On the other hand, compound 9 afforded 10 as a major product and its regioisomer 11 as a minor product in a ratio of 8:2; formation of the above mentioned isomeric mixture involves cis and trans diastereomeric intermediates during the reaction. Treatment of these precursors with Co2(CO)8 in benzene followed by oxidative decomplexation with DMSO yielded in a stereoselective manner the polysubstituted bis-cyclopentanoids 12 and 13. The stereochemistry of 13 was assigned with the help of X-ray analysis. Attempts were made to prepare the tetracyclic systems 15 and 17 using 12 and 13 with 3-acetoxy-2-[(trimethylsilyl)methyl]-1-propene (14); however, the alkylation products 16 and 18 were obtained.
