- ENANTIOSELECTIVE SYNTHESES OF HETEROYOHIMBINE NATURAL PRODUCT INTERMEDIATES
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Enantioselective syntheses of cis- and trans-bicyclic dihydropyran compounds, and other intermediates, en route to heteroyohimbine alkaloids.
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- Enantioselective syntheses of heteroyohimbine natural products: A unified approach through cooperative catalysis
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Alstonine and serpentine are pentacyclic indoloquinolizidine alkaloids (referred to as "anhydronium bases") containing three contiguous stereocenters. Each possesses interesting biological activity, with alstonine being the major component of a plant-based remedy to treat psychosis and other nervous system disorders. This work describes the enantioselective total syntheses of these natural products with a cooperative hydrogen bonding/enamine-catalyzed Michael addition as the key step. The enantioselective total syntheses of the natural products alstonine and serpentine are presented. They proceed through a sequence with a cooperative hydrogen bonding/enamine-catalyzed Michael addition as the key step.
- Younai, Ashkaan,Zeng, Bi-Shun,Meltzer, Herbert Y.,Scheidt, Karl A.
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p. 6900 - 6904
(2015/06/08)
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- Total syntheses of the Strychnos indole alkaloids (-)-tubifoline, (-)-tubifolidine, and (-)-19,20-dihydroakuammicine
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Two different strategies for the synthesis of pentacyclic Strychnos alkaloids in enantiomerically pure form are explored. Both of them involve the use of enantiopure 2-(4-piperidylmethyl)indoles prepared by kinetic resolution of 1-(3-pyridyl)ethanol, followed by partial reduction of the pyridine ring to the tetrahydropyridine level, Claisen rearrangement of the resulting allylic alcohol, and finally Smith indolization. Whereas 2-(4-piperidylmethyl)indole 6 could not be converted to tetracyclic ABDE substructures of Strychnas alkaloids, photocyclization of chloroacetamide 14, derived from (piperidylmethyl)indole 13, satisfactorily afforded the stemmadenine-type tetracycle 15, which was then converted to the alkaloids (-)-tubifoline, (-)-tubifolidine, and (-19,20-dihydroakuammicine.
- Amat, Mercedes,Coll, M.-Dolors,Bosch, Joan,Espinosa, Enric,Molins, Elies
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p. 935 - 948
(2007/10/03)
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- An enantioselective synthesis of the Strychnos alkaloid (-)-tubifoline
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An enantioselective synthesis of the Strychnos alkaloid (-)-tubifoline, involving the kinetic resolution of racemic 1-(3-pyridyl)ethanol, the orthoester Claisen rearrangement of the enantiopure allylic alcohol 5, Smith indolization of the resulting 4-piperidineacetate 6, photocyclization of chloroacetamide 9, and final transannular cyclization, is reported.
- Amat, Mercedes,Coll, Ma-Dolors,Passarella, Daniele,Bosch, Joan
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p. 2775 - 2778
(2007/10/03)
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