Total synthesis of (-)-indolizidine 167B via an unusual Wolff rearrangement from an alpha,beta-unsaturated diazoketone

A concise synthesis of the (-)-indolizidine alkaloid 167B and two formal syntheses of (-)-indolizidine 209D and (-)-coniceine are described in just three steps from an alpha,beta-unsaturated diazoketone, via an unusual photochemical Wolff rearrangement. Preparation of the unsaturated diazoketone is straightforward from N-Cbz-prolinal and a 3-diazo-2-oxopropylphosphonate, employing a Horner-Wadsworth-Emmons reaction. The strategy should be feasible and easily adaptable to the synthesis of other indolizidine alkaloids and analogues. (C) 2011 Elsevier Ltd. All rights reserved.FAPESP (Research Supporting Foundation of the State of Sao Paulo)FAPESP (Research Supporting Foundation of the State of Sao Paulo)CNPqCNP

Preparation of alpha,beta-Unsaturated Diazoketones Employing a Horner-Wadsworth-Emmons Reagent

A new method for the preparation of alpha,beta-unsaturated diazoketones from aldehydes and a Horner-Wadsworth- Emmons reagent is reported. The method was applied to the short synthesis of two substituted pyrrolidines.FAPESP (Research Supporting Foundation of the State of Sao Paulo)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPqConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Reação entre fenilnitrometanos e enoato derivado do D-manitol na presença de TBAF ou DBU: adição conjugada sin-seletiva e reação de NEF consecutiva The reaction between Phenylnitromethanes and enoate derived from D-mannitol in the presence of TBAF or DBU: tandem syn-selective conjugate addition and NEF reaction

<abstract language="eng">A tandem syn-selective conjugate addition - Nef reaction was observed when phenylnitromethane and oxygenated derivatives were allowed to react with an enoate derived from D-mannitol at rt in the presence of TBAF or DBU. While nitro-adducts predominate after 4h of reaction, the corresponding ketones were the main products after 12-24h of reaction. The Nef reaction occurred without racemization of the stereogenic center generated in the conjugate addition step

alpha,beta-Unsaturated Diazoketones as Platforms in the Asymmetric Synthesis of Hydroxylated Alkaloids. Total Synthesis of 1-Deoxy-8,8a-diepicastanospermine and 1,6-Dideoxyepicastanospermine and Formal Synthesis of Pumiliotoxin 251D

A versatile and concise approach for the stereoselective synthesis of mono-, di-, and trihydroxylated indolizidines is presented in four to six steps from Cbz-prolinal and a diazophosphonate. The key steps involved a Wolff rearrangement, followed by a stereoselective dihydroxylation/epoxidation reaction, from an alpha,beta-unsaturated diazoketone. The strategy also permits extension to the synthesis of many natural hydroxylated indolizidine alkaloids as demonstrated in the formal synthesis of pumiliotoxin 251D.FAPESP (Research Supporting Foundation of the State of Sao Paulo)FAPESP (Research Supporting Foundation of the State of Sao Paulo) [2012/04685-5, 2008/09653-9]CNPq [307905/2009-8, 160428/2011-4]CNP

CCDC 947093: Experimental Crystal Structure Determination

Related Article: Vagner D. Pinho, David J. Procter, and Antonio C. B. Burtoloso|2013|Org.Lett.|15|2434|doi:10.1021/ol400903

α,β-Unsaturated Diazoketones as Platforms in the Asymmetric Synthesis of Hydroxylated Alkaloids. Total Synthesis of 1‑Deoxy-8,8a-diepicastanospermine and 1,6-Dideoxyepicastanospermine and Formal Synthesis of Pumiliotoxin 251D

A versatile and concise approach for the stereoselective synthesis of mono-, di-, and trihydroxylated indolizidines is presented in four to six steps from Cbz-prolinal and a diazophosphonate. The key steps involved a Wolff rearrangement, followed by a stereoselective dihydroxylation/epoxidation reaction, from an α,β-unsaturated diazoketone. The strategy also permits extension to the synthesis of many natural hydroxylated indolizidine alkaloids as demonstrated in the formal synthesis of pumiliotoxin 251D

SmI₂‑Mediated Couplings of α‑Amino Acid Derivatives. Formal Synthesis of (−)-Pumiliotoxin 251D and (±)-Epiquinamide

The coupling between cyclic and acyclic α-amino acid derivatives and methyl acrylate, mediated by samarium diiodide, is described. The method constitutes a powerful tool to construct indolizidine, quinolizidine, and piperidine systems in a straightforward two-step fashion. The formal synthesis of (−)-pumiliotoxin 251D and (±)-epiquinamide is achieved after two or three steps from these amino acid derivatives

SmI₂‑Mediated Couplings of α‑Amino Acid Derivatives. Formal Synthesis of (−)-Pumiliotoxin 251D and (±)-Epiquinamide

The coupling between cyclic and acyclic α-amino acid derivatives and methyl acrylate, mediated by samarium diiodide, is described. The method constitutes a powerful tool to construct indolizidine, quinolizidine, and piperidine systems in a straightforward two-step fashion. The formal synthesis of (−)-pumiliotoxin 251D and (±)-epiquinamide is achieved after two or three steps from these amino acid derivatives