[reaction: see text] Acid-catalyzed condensation of aromatic amines with delta,epsilon-unsaturated aldehydes, followed by intramolecular formal hetero Diels-Alder reaction, is described as a potential route to the cyclopenta[b]quinoline substructure of isoschizozygane alkaloids. Reactions are highly diastereoselective and produce adducts with up to four contiguous stereocenters.
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Vallesamidine and schizozygane alkaloids: rearranged monoterpene indole alkaloids and synthetic endeavours.
Nat Prod Rep
May 2024
Department of Biomedical Engineering and Diagnostic Pharmacy, China Pharmaceutical University, Nanjing, 211198, China.
Covering 1963 to 2023Monoterpene indole alkaloids are the main sub-family of indole alkaloids with fascinating structures, stereochemistry, and diverse bioactivities (, anticancer, anti-malarial and anti-arrhythmic ). Vallesamidine alkaloids and structurally more complex schizozygane alkaloids are small groups of rearranged monoterpene indole alkaloids with a unique 2,2,3-trialkylated indoline scaffold, while schizozygane alkaloids can generate a further rearranged skeleton, isoschizozygane, possessing a tetra-substituted, bridged tetrahydroquinoline core. In this review, the origin and structural features of vallesamidine and schizozygane alkaloids are introduced, and a discussion on the relationship of these alkaloids with aspidosperma alkaloids and a structural rearrangement hypothesis based on published studies is followed.
View Article and Find Full Text PDFApplication of cross-conjugated heteroaromatic betaines to the synthesis of the schizozygane alkaloid (+/-)-strempeliopine.
J Org Chem
October 2009
Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
An efficient stereocontrolled route to the isoschizozygane alkaloid core has been developed utilizing an intramolecular 1,4-dipolar cycloaddition of a cross-conjugated heteroaromatic betaine. The resulting cycloadduct undergoes loss of COS, and further reduction delivers a 5a-azaacenaphthylene intermediate that was transformed into the isoschizozygane skeleton upon treatment with acid. A variation of this tactic was then employed for a synthesis of the hexacyclic framework of the shizozygane alkaloid (+/-)-strempeliopine.
View Article and Find Full Text PDFDetermination of the absolute configurations of natural products via density functional theory calculations of vibrational circular dichroism, electronic circular dichroism, and optical rotation: the iso-schizozygane alkaloids isoschizogaline and isoschizogamine.
Chirality
March 2008
Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, USA.
The development of density functional theory (DFT) methods for the calculation of vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and transparent spectral region optical rotation (OR) has revolutionized the determination of the absolute configurations (ACs) of chiral molecules using these chiroptical properties. We report the concerted application of DFT calculations of VCD, ECD, and OR to the determination of the ACs of the isoschizozygane alkaloid natural products, isoschizogaline, and isochizogamine, whose ACs have not previously been determined. The ACs of naturally occurring (-)-isoschizogaline and (-)-isoschizogamine, are both determined definitively to be 2R, 7R, 20S, 21S.
View Article and Find Full Text PDFAn approach to the isoschizozygane alkaloid core using a 1,4-dipolar cycloaddition of a cross-conjugated heteroaromatic betaine.
Org Lett
July 2005
Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
[reaction: see text] A new strategy for the synthesis of the isoschizozygane alkaloid core has been developed that is based on a 1,4-dipolar cycloaddition reaction of a cross-conjugated heteroaromatic betaine. The resulting cycloadduct undergoes loss of COS, and further reduction delivers a 5a-aza-acenaphthylene intermediate that was transformed into the isoschizozygane skeleton upon treatment with acid.
View Article and Find Full Text PDFEfficient construction of cyclopenta[b]quinoline core of isoschizozygane alkaloids via intramolecular formal hetero-Diels-Alder reaction.
Org Lett
July 2003
Department of Chemistry, University of Rochester, Rochester, New York 14627-0216, USA.
[reaction: see text] Acid-catalyzed condensation of aromatic amines with delta,epsilon-unsaturated aldehydes, followed by intramolecular formal hetero Diels-Alder reaction, is described as a potential route to the cyclopenta[b]quinoline substructure of isoschizozygane alkaloids. Reactions are highly diastereoselective and produce adducts with up to four contiguous stereocenters.
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