Recent progress in the chemistry of the Stemona alkaloids

Abstract

for postdoctoral work on the total synthesis of erythronolide A. In 1985 he started his independent research program at Unicamp aimed to develop and apply stereoselective methodologies to the total synthesis of natural products such as pheromones, alkaloids and macrolides. Professor Pilli is the recipient of the 1989 Union Carbide Prize, Brazil as the supervisor of the award winner project and of the 1999 Silver Jubilee Award of the Inter-national Foundation for Science, Sweden. He has been a fellow of several national and international scientific organizations and is currently on the Editorial Board of Quimica Nova and Journal of the Brazilian Chemical Society. M. C. Ferreira de Oliveira was born in Fortaleza, CE (Brazil) in 1967. She received her BSc degree from Universidade Regional de Blumenau (Blumenau, SC) in 1992 and her MSc at Universidade Federal do Ceará (Fortaleza, CE) in 1996. Her master degree involved the phytochemical study of Bredemeyera brevifolia (Polygalaceae). In 1996 she joined Professor Pilli's group to develop her PhD work studying the stereochemical outcome of the addition of carbon nucleophiles to cyclic N-acyliminium ions and the application to the synthesis of Stemona alkaloids.

Total synthesis of (±)-stemonamide, (±)-isostemonamide, (±)-stemonamine, and (±)-isostemonamine using a radical cascade

“…1,2 Their tetracyclic structure including contiguous spirocyclic quaternary centers provides attractive target molecules for total synthesis. 3,4 We wish to report herein a total synthesis of (±)-stemonamide (1) and (±)-isostemonamide (2) using a radical cascade as the key step and the synthesis of (±)-stemonamine (3) and (±)-isostemonamine (4) by chemoselective reduction of (±)-1 and (±)-2, respectively.…”

Stemocurtisine, the First Pyrido[1,2-a]azapine Stemona Alkaloid

“…2 A few of these alkaloids do not fit these five structural groups and have a more complex bridged structure or ring structures that most likely arises from initial oxidative cleavage of the pyrrolo [1,2-a] presence of the C-and D-ring system that is typically found in the stemoamide group of alkaloids, including stemofoline (1). 1,6,[9][10][11][12][13][14][15][16][17] The 13 C/DEPT NMR spectra of 2 indicated four methine carbons, and six methylene carbons and, unlike the other Stemona alkaloids, except 1 and its didehydro and 2'-hydroxy derivatives, 2 a quaternary carbon at  120.4 was apparent, indicative of a acetal-like structure (C-9).…”

“…1 The pyrrolo [1,2-a]azepine (1-azabicyclo[5.3.0]decane) nucleus is common to all compounds in these groups. For example, the relatively complex Stemona alkaloid, stemofoline (1), has the typical pyrrolo [1,2-a]azepine A,B-ring structure, characteristic of this class of alkaloids.…”

“…1 The pyrrolo [1,2-a]azepine (1-azabicyclo[5.3.0]decane) nucleus is common to all compounds in these groups. For example, the relatively complex Stemona alkaloid, stemofoline (1), has the typical pyrrolo [1,2-a]azepine A,B-ring structure, characteristic of this class of alkaloids. 2 A few of these alkaloids do not fit these five structural groups and have a more complex bridged structure or ring structures that most likely arises from initial oxidative cleavage of the pyrrolo [1,2-a] presence of the C-and D-ring system that is typically found in the stemoamide group of alkaloids, including stemofoline (1).…”

Synthesis of bicyclic lactams using novel Schmidt reactions

“…The formation of the 1-azabicyclic compound 15 was noteworthy since it contains an important substructure found in many alkaloids, including the Stemona alkaloids, 21 …”