title: Total syntheses of the monoterpene indole alkaloids (±)-alstilobanine A and E and (±)-angustilodine.
abstract: A synthetic strategy has been developed culminating in stereoselective total syntheses of the small class of unusual monoterpenoid indole alkaloids exemplified by alstilobanines A (3) and E (2) and angustilodine (1). A pivotal step includes a novel intermolecular Michael-type addition of an indole ester dianion to a piperidine-derived nitrosoalkene to form the C15, C16 bond of the alkaloids. In addition, an application of the Romo protocol for effecting a stereoselective intramolecular nucleophile-assisted aldol-lactonization was employed, leading to a β-lactone incorporating the requisite cis-fused 2-azadecalin moiety and also setting the C15, C19, C20 relative stereochemistry of the metabolites. It was then possible to stereoselectively effect an aldolization of a dianion derived from this indole ester β-lactone intermediate with formaldehyde to introduce the requisite C16 hydroxymethyl group. Further manipulations of the system ultimately led to the three alkaloids in racemic form.
authors: Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors: Yiqing
authors: Y
authors: Feng
authors: Max M
authors: MM
authors: Majireck
authors: Steven M
authors: SM
authors: Weinreb
mesh_terms: D015394:Molecular Structure; D046948:Secologanin Tryptamine Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D046948:Secologanin Tryptamine Alkaloids; C581079:alstilobanine A; C000590891:alstilobanine E; C000590892:angustilodine