ABSTRACT
The stereocontrolled total synthesis of (+)-pleiocarpamine and the total syntheses of (+)-voacalgine A and (+)-bipleiophylline have been achieved. The scalable and concise 10-step synthesis of (+)-pleiocarpamine features construction of stereochemistry at the C16 position by radical cyclization and that of the highly strained cage-like structure via Pd-catalyzed intramolecular aromatic C-H functionalization. By modifying the biomimetic aerobic oxidative coupling of tryptophane derivatives catalyzed by FePc(CO2H)8, the oxidative coupling of the synthesized (+)-pleiocarpamine with pyrocatechuic acid was established to produce (+)-voacalgine A. The total synthesis of (+)-bipleiophylline was completed by the second coupling of (+)-voacalgine A with (+)-pleiocarpamine or one-pot couplings of 2 equiv of (+)-pleiocarpamine with pyrocatechuic acid.
ABSTRACT
Cordybislactone (3), a new stereoisomer of the 14-membered bislactone clonostachydiol, together with its open ring analog (4), was isolated from the hopper pathogenic fungus Cordyceps sp. BCC 49294. The relative and absolute configurations of 3 were determined by chemical derivatizations, including the modified Mosher's method. The stereochemistry of clonostachydiol was determined using the natural compound isolated from Xylaria sp. BCC 4297. The result revealed that the absolute configuration of clonostachydiol, previously determined by synthesis, should be revised to its enantiomer.
Subject(s)
Anti-Bacterial Agents/chemistry , Cordyceps/chemistry , Lactones/chemistry , Animals , Anti-Bacterial Agents/pharmacology , Antibiotics, Antineoplastic/chemistry , Antibiotics, Antineoplastic/pharmacology , Antitubercular Agents/chemistry , Antitubercular Agents/pharmacology , Cell Line, Tumor , Chlorocebus aethiops , Fermentation , Humans , Lactones/pharmacology , Magnetic Resonance Spectroscopy , Mass Spectrometry , Molecular Structure , Mycobacterium tuberculosis/drug effects , Stereoisomerism , Vero Cells , XylarialesABSTRACT
A bioinspired convergent total synthesis of (+)-haplophytine, a dimeric indole alkaloid with diazabicyclo[3.3.1]nonane and hexacyclic aspidosperma segments, is described. This synthesis involves the direct coupling of the two segments in a AgNTf2 -mediated Friedel-Crafts reaction and construction of the diazabicyclo[3.3.1]nonane skeleton through late-stage chemoselective aerobic oxidation of the 1,2-diaminoethene moiety and a sequential semipinacol-type rearrangement.
