- Benzylidene Acetals of the D-Ribonolactones: a Structural Reassessment
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The product of the reaction of D-ribono-1,4-lactone with benzaldehyde and concentrated HCl has been shown, by X-ray crystallography of its acetate, to be 3,4-O-(R)-benzylidene-D-ribono-1,5-lactone and not the 3,5-acetal as previously suggested; with ZnCl2 as catalyst the products are 2,3-O-(R)- and -(S)-benzylidene-D-ribono-1,4-lactone, the former preponderating.
- Baggett, Neil,Buchanan, J. Grant,Fatah, Moutie Y.,Lachut, C. H.,McCullough, Kevin J.,Webber, John M.
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- Investigations of the Formation of Cyclic Acetal and Ketal Derivatives of D-Ribono-1,4-lactone and 2-Deoxy-D-ribono-1,4-lactone
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The reactions of D-ribono-1,4-lactone, and 2-deoxy-D-ribono-1,4-lactone with benzaldehyde and acetone in acidic media were investigated.The products obtained were isolated and characterized.The 1H NMR spectra of the 1,5-lactone product resulting from the thermodynamically controlled reaction of D-ribono-1,4-lactone with benzaldehyde were examined between 300 K and 200 K in a polar solvent.No conformational changes in the 1,5-lactone ring were observed within this temperature range.Detailed NMR studies showed that the acetalization of D-ribono-1,4-lactoneproceeded with the initial formation of the endo-2,3-acetal derivative, which in the presence of aqueous acids underwent ring expansion and isomerization to the 3,4-acetal of the 1,5-lactone.The endo preference of benzylidene acetals was explained by the transition state conformation of the reactants and the thermodynamic stability of the products, as calculated with molecular mechanics. Key words: D-ribono-1,4-lactone, 2-deoxy-D-ribono-1,4-lactone, acetal, ketal.
- Han, So-Yeop,Joullie, Madeleine M.,Petasis, Nicos A.,Bigorra, Joaquim,Corbera, Jordi,et al.
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- Chiral synthesis of (S)-(+)-γ-hydroxymethyl-γ-butyrolactone
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S-(+)-γ-hydroxymethyl-γ-butyrolactone has been synthesized from D- ribonolactone as chiral template.
- Salas-Reyes
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p. 2187 - 2199
(2007/10/03)
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- Spectroscopic, crystallographic and computational studies of the formation and isomerization of cyclic acetals and ketals of pentonolactones
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The different reactivities of D-ribonolactone, L-arabinonolactone, D-xylonolactone, D-lyxonolactone and 2-deoxy-D-ribonolactone toward benzaldehyde and acetone in acidic media, were examined. The reactions involved complex equilibria and were investigated with extensive 13C NMR studies as well as X-ray crystallographic analysis of selected products. Molecular mechanics (MM2) and semiempirical (PM3 and AM1) calculations of some derivatives were carried out in order to facilitate structural and conformational assignments. The differences in reactivity observed for the reactions of D-pentono-1,4-lactones with benzaldehyde and acetone are rationalized in terms of their structural and conformational features.
- Han,Joullie,Fokin,Petasis
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p. 2535 - 2562
(2007/10/02)
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- A PRACTICAL SYNTHESIS OF 2-DEOXY ALDONOLACTONES VIA A SmI2-MEDIATED α-DEOXYGENATION REACTION
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A one-step deoxygenation of 2-hydroxylactones or their acetates is possible using samarium diiodide as an electron-transfer reagent in conjunction with a proton source.
- Hanessian, Stephen,Girard, Christian,Chiara, Jose Luis
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p. 573 - 576
(2007/10/02)
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- High Yield Reduction of 2-O-Trifluoromethanesulphonate Esters of α-Hydroxylactones to the corresponding 2-Deoxylactones by Lithium Iodide Trihydrate
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Reaction of 2-O-trifluoromethanesulphonate esters of 1,4- and 1,5-α-hydroxy lactones with lithium iodide trihydrate in tetrahydrofuran gives good to excellent yields of the corresponding 2-deoxy lactones.
- Elliot, Russell P.,Fleet, George W. J.,Gyoung, Young Soo,Ramsden, Nigel G.,Smith, Colin
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p. 3785 - 3788
(2007/10/02)
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