1,721,001 research outputs found
A mild hydrogenolytic-hydrolytic conversion of oximes to carbonyl compounds
No full textOximes are converted into the corresponding carbonyl compounds in high yields using Raney-nickel and sodium hypophosphite at pH 5
New syntheses of optically active vitamin E side chain by chemicoenzymatic approach
No full textTwo independent syntheses of enantiomerically pure ( 3R, 7R) -3,7,11-tri-methyldodecan-1-ol (), the C15 tocopherol side chain, are described. Both reaction sequences start from (R)-citrohellol, obtained by baker's yeast reduction of geraniol. One strategy is based on the coupling between (R)-citronellyl bromide and a C5 optically active unit derived from chemical degradation of the common starting template; the other one uses an achiral isoprenic unit and a C10, building block containing two asymmetric carbon atoms generated by microbial reactions
Regio- and stereoselective hydrogenation of methyl substituted pentadien-1-ols by baker's yeast
No full text(E)-2-methyl- and (E)-3-methyl-2,4-pentadien-1-ols are reduced to (S)-2-methyl- and (S)-3-methyl-4-penten-1-ols, respectively, using baker's yeast as a regio- and stereoselective reagent. This microbiological conversion provides an efficient route to bifunctional and enantiomerically pure C6-building blocks containing the C' -CH(Me )-C'' grouping
A C-glucosylated 5-methylchromone from Kenya aloe
No full textA new bitter C-glucoside, aloeresin D, was isolated from a commercial sample of Kenya aloe. Its structure was assigned as 8-C-β-d-[2-O-(E)-p-coumaroyl]glucopyranosyl-2-[(R)-2-hydroxy]propyl-7-methoxy-5-methyl-chromone by spectral data and chemical transformations
STUDIES ON ALOE .2. ALOERESIN-C, A BITTER C,O-DIGLUCOSIDE FROM CAPE ALOE
No full textA new bitter C,O-diglucoside, aloeresin C, was isolated from commercial Cape aloe. Its structure, 2-acetonyl-7-O-β-D-glucopyranosyl-8-C-β-D-[2′-O-(E)-p-coumaroyl]glucopyranosyl-5-methylchromone, was established by spectral and chemical methods
Synthesis of naturally occurring 2,5-dialkylchromones : part 1. Synthesis of aloesone and aloesol
No full textBaker yeast hydrogenation of carbonyl activated double-bonds-enantioselective synthesis of the (S)-form of the dihydroterpenediol secreted by danaus-chrysippus and of a pheromone of callosobruchus-chinensis L
Full text linkThe (S)-forms of (E)-3,7-dimethyl-2-octene-1,8-diol (secreted by male danaid butterflies) and of (E)-3,7-dimethyl-2-octene-1,8-dioic acid (a pheromone of the azuki bean weevil) were synthesized via stereoselective hydrogenation by baker’s yeast of the carbonyl activated double bond of achiral precursors
A convenient synthesis of both the anomers of ethyl (2,3,4,6-tetra-O-benzyl-D-glucopyranosyl)acetate
No full textThe α- and β-anomers of ethyl (2,3,4,6-tetra-O-benzyl-D-glucopyranosyl) acetate, useful intermediates for the synthesis of alkyl C-glucosides, can be obtained in good yields by reaction of tetra-O-benzylglucose with triethyl phosphonoacetate according to the Wittig-Horner procedure
Aloenin B, a New Diglucosylated 6-Phenyl-2-pyrone from Kenya Aloe
No full textA new 6-phenyl-2-pyrone O,O-diglucoside, aloenin B, was isolated from commercial Kenya aloe. Its structure, 6- {2-O-β-D-[2-O-(E)-p-coumaroyl} glucopyranosyl-4-O-β-D-giucopyranosyl-6-methyl } phenyl-2-pyrone (1), was established by spectral methods and chemical transformations
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