78342-33-3Relevant academic research and scientific papers
Out-of-Ring Claisen Rearrangement are Highly Stereoselective in Pyranoses: Routes to gem-Dialkylated Sugars
Tulshian, Deen Bandhu,Tsang, Raymond,Fraser-Reid, Bert
, p. 2347 - 2355 (2007/10/02)
The Claisen rearrangement has been evaluated as a means for stereoselective creation of functionalized geminal substituents at C-2 and C-3 of hexopyrano systems.C-2 and C-3 keto sugars react with Wittig reagents to give α,β-unsaturated esters, one geometric isomer being obtained in each case.Reduction of the ester and trans vinylation with ethyl vinyl ether leads to allyl vinyl ethers wich are thermolysed in refluxing benzonitrile.The oxy-Cope rearrengement proceeds with complete stereoselectivity, the folding pattern being always from the β-face of the pyranose ring.Thus, the acetaldehyde moiety ends up axially oriented at C-2 and equatorially oriented at C-3.These stereochemical results are not affected by neighboring oxygen substituents nor by the presence or absence of an anomeric alkoxyl functionality.
Highly Stereoselective Routes to Functionalized Geminal Alkyl Derivatives of Carbohydrates
Fraser-Reid, Bert,Tsang, Raymond,Tulshian, Deen Bundhu,Sun, King Mo
, p. 3764 - 3767 (2007/10/02)
2-, 3-, and 4-Keto derivatives of some α-D-hexopyranosides react with Ph3P=CHCOOEt to give a single geometric isomer in each case, which is readily converted into an allyl vinyl ether.Claisen rearrangements of the latter proceed with high stereoselectivit
