40773-64-6Relevant academic research and scientific papers
Site-selective catalysis of phenyl thionoformate transfer as a tool for regioselective deoxygenation of polyols
Sanchez-Rosello, Maria,Puchlopek, Angela L. A.,Morgan, Adam J.,Miller, Scott J.
, p. 1774 - 1782 (2008/09/18)
(Chemical Equation Presented) We report the application of peptide-embedded imidazoles as catalysts for the site-selective delivery of the phenyl thionoformate unit as a prelude to deoxygenation reactions of polyols. Methodology was developed that allows for the synthesis of thiocarbonyl derivatives based on a combination of additives that include N-alkylimidazoles and FeCl3 as co-catalysts. The use of this reagent combination leads to increased reaction rates and efficient yields relative to those of simple base-mediated reactions. In terms of controlling regioselectivity during the course of polyol modification, we found that histidine-containing peptides, in combination with FeCl3, could lead to modulation of the product distribution. Through screening of peptides and control of reaction conditions, products could be observed that reflected both the inherent preference of substrates and also reversal of inherent selectivity.
A Carbohydrate Approach to Polyol Fragments of Amphotericin and the Trienomycin- and Mycotrienin Antibiotics
Fuerstner, Alois,Baumgartner, Judith
, p. 8541 - 8560 (2007/10/02)
Hydrolytically labile ω-chloro-ω-phenylthioglycosides, obtained from the corresponding ω-phenylthioglycosides on treatment with NCS in CCl4, are readily dealkoxyhalogenated with Zn/Ag-graphite in anhydrous solvents affording enantiomerically pure synthons
An Efficient Deoxysugar Synthesis using Bu4NBH4 via an SN2 Reduction
Sato, Ken-ichi,Hoshi, Toshio,Kajihara, Yasuhiro
, p. 1469 - 1472 (2007/10/02)
Deoxysugar derivatives were prepared from the corresponding triflate, tosylate, halogen, and epoxide derivatives.Employing the tetrabutylammonium tetrahydroborate reagent, the deoxygenation proceeds via an SN2 type displacement in good yield.
1,6-anhydro-β-hexopyranose derivatives and their use as herbicides and plant growth regulators
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, (2008/06/13)
Herbicidal and/or plant-growth regulatory compositions comprising, together with a carrier and/or surface-active agent, an effective amount of at least one herbicidal and/or plant growth regulatory active agent selected from compounds of formula (I) STR1 (in which R represents an optionally substituted aralkyl group, X represents an O--, N-- or S-linked organic group, an optionally substituted hydrocarbyl group, a halogen atom, a hydroxy, amino, alkoxyamino, nitro, cyano, azido, sulpho or phospho group, or together with the group R2e, X may represents a ketonic oxygen atom --O-- or a group of formula --CH2 O--; R1e represents a hydrogen atom or an optionally substituted hydrocarbyl group, or a formyl group; R2e represents a hydrogen atom, a hydroxy group or an optionally substituted hydrocarbyl or O-linked hydrocarbyl group, or, together with the group X, R2e may represent a ketonic oxygen atom --O-- or a group of formula --CH2 O--; R3a represents a hydrogen atom, a hydroxy group or an optionally substituted alkoxy, alkenyloxy, aralkoxy or C1-4 hydrocarbyl group; R3e represents a hydrogen atom, a hydroxy group or an optionally substituted hydrocarbyl or O-linked hydrocarbyl group; and R4e represents a hydrogen atom or an optionally substituted hydrocarbyl group) and enantiomers and salts thereof. Methods for preparing the compounds of formula (I) are described; the compositions are valuable as herbicides and/or plant-growth regulants, particularly for use with crops such as soya, rape, sugar-beet, cotton, wheat, maize and rice.
Stereochemical dependence of the mechanism of deoxygenation, with lithium triethylborohydride, in 4,6-O-benzylidenehexopyranoside p-toluenesulfonates
Baer, Hans H.,Mekarska-Falicki, Miroslawa
, p. 3043 - 3052 (2007/10/02)
Lithium triethylborohydride was shown to react with methyl 4,6-O-benzylidene-α-D-hexopyranoside 2- and 3-tosylates, and 2,3-ditosylates, in the manno, allo, and altro configurational series both by O-S fission (O-desulfonylation) and by C-O fission (C-desulfonyloxylation), to produce carbinol and deoxy functions, respectively.The results were compared with those previously obtained with the corresponding gluco and galacto isomers, and the degree of facility of the cleavage reactions was seen to depend on the position of the sulfonic ester groups and the overall configuration of the molecules.The mechanism of reductive desulfonyloxylation also depended on configuration and was demonstrated to involve intermediary epoxide formation or displacement by internal hydride shift as the principal paths; competing elimination and direct nucleophilic displacement were found to occur in the allo series, whereas reduction accompanied by ring contraction has thus far been encountered only in the conformationally less constrained, cis-fused acetal system of the galacto series.Like the borohydride reagent, lithium aluminum hydride was found to react (though much more slowly) with the altro 2,3-ditosylate by the epoxide-mediated mechanism, although the latter hydride is known to desulfonyloxylate the α-D-gluco-isomer by a different, intramolecular reduction mechanism.
Synthesis of bulgecinine: A new amino acid in bulgecins
Wakamiya,Yamanoi,Nishikawa,et al.
, p. 4759 - 4760 (2007/10/02)
Bulgecinine, a new proline type amino acid in bulgecins, was synthesized stereospecifically by use of D-glucose as a chiral precursor.
DESULFONYLOXYLATION OF SOME SECONDARY p-TOLUENESULFONATES OF GLYCOSIDES BY LITHIUM TRIETHYLBOROHYDRIDE; A HIGH-YIELDING ROUTE TO 2- AND 3-DEOXY SUGARS
Baer, Hans H.,Hanna, Hanna R.
, p. 19 - 42 (2007/10/02)
Lithium triethylborohydride (LTBH) reacts readily with p-toluenesulfonates of methyl 4,6-O-benzylidene-α-D-glucopyranoside (4) to give deoxyglycosides in >90percent yield.Thus, the 2,3-ditosylate (1) and the 3-monotosylate (2) thereof afford methyl 4,6-O-benzylidene-2-deoxy-α-D-ribo-hexopyranoside (7) in highly regio- and stereo-selective reactions that proceed via methyl 2,3-anhydro-4,6-O-benzylidene-α-D-allopyranoside (6), and the 2-monotosylate (8) of 4 gives the 3-deoxy-α-D-arabino isomer (12) of 7 via the corresponding 2,3-anhydro-α-D-mannopyranoside 11.In the series of the corresponding β anomers, the 3-monotosylate 14 and the 2-monotosylate 16 are similarly desulfonyloxylated, with equal ease, but furnish mixtures of regioisomeric deoxyglycosides, namely, the 3- and 2-deoxy-β-D-ribo derivatives 20 and 21, and the 2- and 3-deoxy-β-D-arabino derivatives 22 and 23, respectively.It could be shown that this difference is due to the failure of the intermediary, β-glycosidic epoxides 18 and 19 (the anomers of 6 and 11) to obey the Fuerst-Plattner rule in their reductive ring-opening with LTBH.The β-glycosidic 2,3-ditosylate 15 reacts less readily, and gives 20-23, with 20 preponderating.The 2-O-methyl-3-O-tosyl-β-D-glucopyranoside 24 is partly desulfonylated and partly desulfonyloxylated, whereas its 3-O-methyl-2-O-tosyl isomer 27 undergoes desulfonylation exclusively.The reductions of 1, 2, and 8 by LTBH are compared with those previously effected by lithium aluminum hydride, which are slower, involve considerable desulfonylation, and afford lower yields of deoxyglycosides, with the main products differing from those obtained by the action of LTBH.Mechanistic differences associated with the two reductants are discussed.
An investigation of the Kishner elimination as a route to dideoxy sugars
Wickremeshinghe, L. Kirthi G.,Slessor, Keith N.
, p. 2628 - 2632 (2007/10/02)
Methyl 4,6-O-benzylidene-2-O-p-toluenesulphonyl-α-D-ribohexopyranosid-3-ulose has been used as a substrate for an investigation of the Kishner elimination as a route to deoxygenated sugars.The conditions of the reaction of the ketotosylate with hydrazine
Process for deoxygenating secondary alcohols
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, (2008/06/13)
The process for removing a secondary hydroxyl group from an organic compound having at least one secondary hydroxyl group and having any amino groups protected, comprises the reaction of a reactive ester of said secondary hydroxyl group selected from the group consisting of an O-alkylthioester and an O-alkylselenoester with at least one mole of an organotin hydride, preferably tri-n-butylstannane, in an inert, aprotic solvent at a temperature of at least about 100° C and under an inert atmosphere. The process is particularly useful in removing secondary alcohols in aminoglycoside antibiotics to produce deoxy derivatives thereof having antibacterial activity. Also described are novel O-sec.-alkylthiobenzoate, O-sec.-alkyl-S-methylxanthate, N-(sec.-alkoxythiocarbonyl)-imidazole esters, and di-O-alkylthiocarbonates having at least one secondary O-alkyl group, useful intermediates of the claimed process.
