Vinylogous Mannich reactions. Stereoselective formal synthesis of pumiliotoxin 251D

Martin, Stephen F.; Bur, Scott K.

doi:10.1016/s0040-4020(99)00452-4

Cited by 53 publications

(30 citation statements)

References 33 publications

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“…For this purpose, alcohol 6 was subjected to Swern oxidation (DMSO, (COCl) 2 , iPr 2 NEt, −78 to 0 °C, 3 h), and the resulting keto-lactam 7 treated with MeMgI in diethyl ether (−78 to 0 °C, 1 h), which gave alcohols 5 / 5a as an inseparable mixture of diastereomers in a ratio of 1:2.2 (combined yield: 47% over 2 steps) (Scheme 1). A comparison of spectral data ( 1 H and 13 C NMR) of our products 5 / 5a with those reported [12,22,28] showed that the desired (8 S ,8a S )- 5 was the minor diastereomer. Similar results have been reported by Nubbemeyer [27] and Li [8].…”

Section: Resultssupporting

confidence: 65%

Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A

Zhang¹,

Zhang²,

Huang³

2013

Beilstein J. Org. Chem.

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SummaryA concise enantioselective synthesis of the advanced intermediate 5 for the synthesis of pumiliotoxins (Gallagher’s intermediate) is described. The synthesis started from the regio- and trans-diastereoselective (dr = 98:2) reductive 3-butenylation of (R)-3-(tert-butyldimethylsilyloxy)glutarimide 14. After O-desilylation and Dess–Martin oxidation, the resulting keto-lactam 10 was subjected to a highly trans-stereoselective addition of the methylmagnesium iodide to give carbinol 11 as sole diastereomer. An efficient ring closure procedure consisting of ozonolysis and reductive dehydroxylation provided the indolizidine derivative 5, which completed the formal enantioselective total synthesis of pumiliotoxins 251D and 237A.

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Section: Resultssupporting

confidence: 65%

Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A

Zhang¹,

Zhang²,

Huang³

2013

Beilstein J. Org. Chem.

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“…Martin started from -pyroglutamate. [5] The key step in building up the target was described as a vinylogous Mannich reaction between the furan unit and the 2-methoxypyrrolidine in the presence of a Lewis acid. Finally, the stereodirecting hydroxymethyl group of the five-membered ring was removed by Raney Ni-mediated reduction.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of the Bicyclic Core of Pumiliotoxins

et al. 2002

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Keywords: Medium rings / Ring contractions / Ring expansion / Sigmatropic rearrangements / ZwitterionsThe bicyclic core of the pumiliotoxins was synthesized in nine to eleven steps starting from L-(−)-proline. This chiral pool starting material was initially converted into an optically active 2-vinylpyrrolidine by standard operations. The first key step allowed the generation of a nine-membered ring lactam by means of a zwitterionic aza-Claisen rearrangement. The 1,4 chirality transfer was found to be low, but the double bond of the azoninone was generated with an exclusive trans configuration in a planar-S arrangement. The mixture of diastereomers thus obtained was immediately epoxid-

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“…119 Catalytic hydrogenation of 239 , followed by a lactone–lactam rearrangement delivered 240 . The hydroxymethyl group in 240 , which had fittingly served its purpose of directing facial selectivity in the vinylogous Mannich reaction, was removed using Raney-Ni according to the method of Kraft to give 241 .…”

Section: Applications Of Vinylogous Mannich and Related Reactionsmentioning

confidence: 99%

Natural Products and Their Mimics as Targets of Opportunity for Discovery

Martin

2017

J. Org. Chem.

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Diverse structural types of natural products and their mimics have served as targets of opportunity in our laboratory to inspire the discovery and development of new methods and strategies to assemble polyfunctional and polycyclic molecular architectures. Furthermore, our efforts toward identifying novel compounds having useful biological properties led to the creation of new targets, many of which posed synthetic challenges that required the invention of new methodology. In this Perspective, selected examples of how we have exploited a diverse range of natural products and their mimics to create, explore, and solve a variety of problems in chemistry and biology will be discussed. The journey was not without its twists and turns, but the unexpected often led to new revelations and insights. Indeed, in our recent excursion into applications of synthetic organic chemistry to neuroscience, avoiding the more-traveled paths was richly rewarding.

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Vinylogous Mannich reactions. Stereoselective formal synthesis of pumiliotoxin 251D

Cited by 53 publications

References 33 publications

Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A

Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A

Synthesis of the Bicyclic Core of Pumiliotoxins

Natural Products and Their Mimics as Targets of Opportunity for Discovery

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