82110-06-3Relevant academic research and scientific papers
Action of Alkali on O-Benzylated Aldoses: A Simple Rationalization of Some Reactions Occurring in Alkaline Media
Anastasia, Mario,Allevi, Pietro,Ciuffreda, Pierangela,Fiecchi, Alberto,Scala, Antonio
, p. 3054 - 3058 (2007/10/02)
Treatment of some O-benzyl-protected aldopyranoses and aldofuranoses with sodium 2-propoxide or K2CO3 brought about their equilibration and the loss of the elements of benzyl alcohol, with concomitant formation of a Z aldehyde.The latter rearranged rapidl
Boron Enolates in Stereoselective Syntheses of 2-Enitols from O-Benzyl Aldoses by Reaction with Borohydride in 2-Propanol. Configuration of E and Z Enols from Proton Relaxation Rates
Rao, Vanga S.,Perlin, Arthur S.
, p. 3265 - 3269 (2007/10/02)
Isomerically pure E and Z forms of 2,4,6-tri-O-benzyl-2-dehydro-3-deoxy-D-erythro-hex-2-enitol (4 and 3, respectively) were synthesized from 2,3,4,6-tetra-O-benzyl-D-glucopyranose by reactions employing sodium borohydride and 2-propanol under differing co
Regioselective eliminations in reactions of carbohydrate derivatives with superoxide, or with borohydride in 2-propanol
Rao, Vanga S.,Perlin, Arthur S.
, p. 333 - 338 (2007/10/02)
The reaction between 2,3,4,6-tetra-O-benzyl-1,5-di-O-mesyl-D-glucitol (2) and potassium superoxide resulted in the loss of H-4 and the 5-mesyloxy (as well as 1-mesyloxy) substituent, and an almost quantitative conversion into enol ether 4, i.e., 1,3,4,5-tetra-O-benzyl-3-dehydro-2-deoxy-L-threo-hex-2-enitol.When the reaction was performed with 8, in which the 1-O-mesyl group (of 2) is replaced by O-(methoxy)trityl, the outcome was wholly different: an olefin was formed through the removal of a primary (H-6) rather than a secondary (H-4) proton, and nucleophilic displacement also took place.Results similar to those for 8 were obtained with the 2-epimer of 2, i.e., 2,3,4,6-tetra-O-benzyl-1,5-di-O-mesyl-D-mannitol (12).It is suggested that selective displacement of the 1-O-mesyl group of 2 by superoxide generates a 1-peroxy anion (6) that abstracts H-4 intramolecularly, promoting concomitant loss of the 5-mesyloxy group.The transition state for proton abstraction within anion 6 appears to be more stable than that of the corresponding anion in the manno series, accounting for the different reaction routes for 2 and 12.Elimination occured also in the reduction of 2,3,4,6-tetra-O-benzyl-D-glucopyranose with sodium borohydride in 2-propanol, en route to 2, affording 2,4,6-tri-O-benzyl-2-dehydro-3-deoxy-D-threo-hex-2-enitol (21).The (1)H nmr spectra of alditol derivatives 2, 8, and 12 show that these molecules depart substantially from extended zigzag conformations, in contrast to configurationally related peracetylated acyclic derivatives.
