1,721,060 research outputs found
A Pd-Mediated Approach to the Synthesis of an Unusual beta-Hydroxytryptophan Amino Acid Constituent of Cyclomarin A.
No full textA synthetic approach based on a palladium-mediated vinylation of indole derivatives was established for the preparation of 5, a key intermediate in the synthesis of N-(tert-butoxycarbonyl)-L-1H-[(R)-1,1-dimethyl-2,3-epoxypropyl]-beta-hydroxytryptophan ethyl ester (6). Unsatisfying yields were obtained using N-alkyl-3-haloderivatives. The best method proved to be the oxidative coupling on 3-unsubstituted indole derivative
Microwave accelerated Wittig reactions of stabilized phosphorus ylides with ketones under solvent-free conditions
No full textMicrowave irradiation accelerates some difficult Wittig reactions of stable phosphorus ylides (e.g. 1) with ketones. Irradiation in a domestic microwave oven of the mixture of reactants, in absence of solvents, allowed to obtain, in shorter times, an improvement of tranformation yields over conventional heating method
Occurrence of Olepupuane In Two Mediterranean Nudibranchs - A Protected Form of Polygodial
No full textFirst total synthesis of natural aplyolides B and D, ichthyotoxic macrolides isolated from the skin of the marine mollusk Aplysia depilans
No full textA convergent pathway is described for the synthesis of the marine macrolides aplyolides B (2) and D (3). Stereoselective preparation of a key fragment was achieved by Sharpless asymmetric dihydroxylation of eneyne 10
Potential Alarm Pheromones From the Mediterranean Opisthobranch Scaphander lignarius
No full textTwo new w-phenyl conjugated trienones, lignarenone-A (2) and lignarenone-B (3), are the main
metabolites isolated from the dorsum acetone extract of Scaphander lignarius. Their structures, closely related
to 3-methyl navenone-B (1) a minor component of the alarm pheromone mixture of the opisthobranch Navonax
inermis, were characterized by spectral methods
Janolusimide, A Lipophilic Tripeptide Toxin From the Nudibranch Mollusk Janolus-cristatus
No full textTke structure of janolusimide, a lipophilic tripeptide toxic to mice isolated from the nudibranch mollusc Janolus cristatus, has been established by spectroscopic and chemical means
New Propionate-derived Metabolites From Aglaja-depicta and From Its Prey Bulla-striata (opisthobranch, Mollusks)
No full textTwo new polypropionate metabolites aglajne-2 (14) and -3 (2) and the previously known aglajne-1 (1) have been isolated from the opisthobranch mollusc Bulla striata, a prey of the opistobranch Aglaja depicta in which
these compounds were first detected. This finding establishes the dietary origin of these metabolites in A. depicta.
The structures were determined by extensive use of 'H and 13C NMR techniques on the compounds and on their
derivatives and by chemical proofs. Two additional compounds (12 and 13), isolated as racemic diastereoisomers,
are artifacts originating from aglajne-2 (14) during the extraction and purification procedures. The relative and
absolute stereochemistry at C-3 and C-6 of aglajne-1 (1) and -3 (2) has been also determined
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