Andre Lubineau

Water-promoted organic reactions. Michael addition of nitroalkanes to methylvinylketone under neutral conditions

Abstract Nitromethane and nitroethane when diluted in water, under neutral conditions, react easily, without any catalyst, with Michael acceptors, such as methylvinylketone. The rate of the reaction is enhanced in sugar aqueous solutions.

New strategy in the synthesis of 3-deoxy-D-manno-2-octulosonic acid (KDO), 2-deoxy-KDO and thioglycoside of KDO

Abstract To take advantage of synthetic intermediates on the way to KDO, we developed a new strategy based on an aqueous hetero Diels-Alder reaction with a water-soluble diene derived from D-glyceraldehyde, followed by a dihydroxylation of the newly created double bond. The stereoselectivities of these reactions were investigated to give rise to 2-deoxy-KDO, which was sulfenylated via the enolate to yield β-thioglycoside, the hydrolysis of which led to KDO.

Lithium Triflate as a New Promoter of Glycosylation Under Neutral Conditions 1

Abstract The glycosyl donors 2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl trichloroacetimidate and 3,4,6-tri-O-benzyl-α-D-fucopyranosyl trichloroacetimidate were activated under neutral conditions with a catalytic amount (0.05 equiv) of lithium triflate and reacted with a series of alcohols including an acid sensitive sugar to give the corresponding glycosides in high yields. The stereoselectivity of the glycosylation was improved by introducing a participating group next to the anomeric position. 1. Presented at the French Chemical Society Meeting, Palaiseau, Sept. 1995.

Water-promoted claisen sigmatropic rearrangement using glyco-organic substrates. Chiral auxiliary-mediated induction

Abstract The Claisen sigmatropic rearrangement with glyco-organic substrates is greatly accelerated in water. Moreover, the ability of glucose to function as a chiral auxiliary is illustrated in the preparation of 4-pentene-1,3-diol , obtained for the first time in pure enantiomeric form.

High-Yielding One-Step Conversion of D-Glucose and D-Galactose to the Corresponding α and β Methyl-D-glucofuranosides and Galactofuranosides

Abstract D-Glucose and D-Galactose are transformed to the corresponding α and β -Methyl D-Glucofuranosides in good yields using methanol and Ferric chloride as catalyst.

Aqueous hetero Diels-Alder reactions: The carbonyl case.

Abstract Commercially available aqueous solution of glyoxylic acid, pyruvaldehyde and glyoxal were shown to react with cyclic or non-cyclic dienes to give the corresponding cycloadducts and/or α-hydroxy γ-lactones. Activated ketone (Pyruvic acid) was shown to react as well in the same conditions.

A Concise Synthesis of (±) Ketodeoxyheptulosonic Acid Derivatives Via Aqueous Hetero Diels Alder Reaction and NBS Mediated Dibromination

Abstract Cycloaddition of sodium glyoxylate, in water, onto penta-2,4-dienol provided 2-deoxyheptulosonic acid derivatives. Activation of the anomeric carbon was achieved through NBS mediated C-2-C-3 dibromination.

Aqueous cycloaddition using glyco-organic substrates. Facial stereoselectivity in Diels–Alder reactions of a chiral diene derived from D-glyceraldehyde

The preparation of a new chiral, water-soluble E-diene, which could be considered as the simplest diene obtainable from the simplest sugar, is described, along with its use in cycloaddition with acrylaldehyde. Water, as the solvent, enhanced the rate of the Diels–Alder reaction, promoted complete regio- and endo-selectivity, and improved a like(anti) facial selectivity, compared with the results obtained with organic solvents.

Stereochemical Study of Cycloadditions Using Erythrose and Threose Based Dienes as Source of 2-Nonulosonic Acid Analogs

Abstract The stereochemical outcome of the hetero Diels Alder reaction of an erythrose based diene with sodium glyoxylate was rationalized by preparing the same compounds via decarboxylation of 2-carbethoxy-2-deoxy-2-ulosonic esters, obtained by cycloaddition with diethyl ketomalonate. Further chemical transformations of cycloadducts allowed us to prepare a series of new 2-nonulosonic acid derivatives.

Ring Opening of Benzyl β-D-Galactoside Cyclic Sulfates into Galactose Monosulfates. New Access to 6-Deoxy-Galacto-Hex-5-Enopyranoside and 4-Deoxy-3-Ketogalactopyranoside.

ABSTRACT The behavior of 3,4- and 4,6-cyclic sulfates derived from benzyl 2,6- and 2,3-di-O-benzyl-β-D-galactopyranosides toward hydrolysis has been studied using aqueous sodium hydroxide under various conditions. Starting from benzyl 2,6-di-O-benzyl-3,4-O-sulfuryl-β-D-galactopyranoside (5), the reaction with aq NaOH in THF gave both 3- and 4-monosulfates 7 and 8 (83%, in 68:32 ratio), while the reaction in DMF led unexpectedly to the 4-deoxy-3-keto derivative 10 in 77% yield after acidic hydrolysis of the intermediate enolester 9. On the other hand, when benzyl 2,3-di-O-benzyl-4,6-O-sulfuryl-β-D-galactopyranoside (6) was treated with aq NaOH in THF, a mixture of benzyl 2,3-di-O-benzyl-6-deoxy-4-O-(sodium sulfonato)-α-L-arabino-hex-5-enopyranoside (11) and benzyl 2,3-di-O-benzyl-4-deoxy-6-O-(sodium sulfonato)-α-L-threo-hex-4-enopyranoside (12) (in 65:35 ratio) was obtained in 93% yield, giving a new and rapid access to 11, a potential precursor of L-sugars derivatives. Alternatively, BzONBu4 gave a regiospecific opening reaction of 6 and led to the 6-O-benzoate 4-O-sulfate derivative (13) in excellent yield.