An expedient synthesis of (±)-γ-lycorane

Hoang-Cong, Xuân; Quiclet‐Sire, Béatrice; Zard, Samir Z.

doi:10.1016/s0040-4039(99)00146-x

Cited by 51 publications

(16 citation statements)

References 21 publications

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“…The key step in the synthesis of (±)‐ γ ‐lycorane by Zard et al involved generation of amidyl radical 47 from precursor 46 . Subsequent C 5x C 6x double cyclization led to a 6:4 mixture of the desired 48 and undesired regioisomers (Scheme ) 70. The major isomer 48 was reduced to (±)‐ γ ‐lycorane with lithium aluminum hydride.…”

Section: Two‐stage Unimolecular Free‐radical Cascadesmentioning

confidence: 99%

Programming Organic Molecules: Design and Management of Organic Syntheses through Free-Radical Cascade Processes

McCarroll

Walton

2001

Angew. Chem. Int. Ed.

233

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Cascade, domino, or tandem processes, that link together two or more transformations in one pot, are increasing in popularity because they lead to improvements in synthetic efficiency and decreases in environmental impact. Not only do these cascades contain choice mechanistic gems but they also deliver compact and elegant syntheses of complex natural products. Longer cascades require more functional groups precisely configured within carefully designed initial molecular architectures. Such “purposeful” molecules can be thought of as chemical algorithms.This article surveys the phenomenal range of unimolecular free‐radical cascades. A convenient system for classifying free‐radical cascades is described that is useful for evaluating and comparing cascades and aids the design of synthetic routes to polycyclic structures.Double cyclization cascades lead to cyclopentylcyclopentane or bicyclo[3.3.0]octane derivatives. Precursors that contain a ring as a template have been used to control stereochemistry in syntheses of triquinanes and many related compounds. Of the cascades containing ring‐cleavage steps, the most useful are the ring expansions which have opened up new synthetic routes to medium ring polycycles.The key design features of three‐stage unimolecular free‐radical cascades that yielded steroid structures, are linear arrays of radical acceptor units associated with methyl groups distributed every fifth C‐atom in the precursor polyenes. Ring cleavage is the reverse of cyclization. In special, symmetrical structures, therefore, this led to sequences that were reversible, thus launching endlessly repeating cascades supported by delightfully fluxional structures. The science of “programming” organic molecules to achieve particular target structures is maturing rapidly. Coordination and classification of the welter of information in this area is intended to facilitate design and hence to extend the range and complexity of attainable structures.

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Section: Two‐stage Unimolecular Free‐radical Cascadesmentioning

confidence: 99%

Programming Organic Molecules: Design and Management of Organic Syntheses through Free-Radical Cascade Processes

McCarroll

Walton

2001

Angew. Chem. Int. Ed.

233

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“…The core challenge can be attributed to the deficiency of a convenient route for the generation of relatively stable nitrogen-centred radical species. [4][5][6][7] Recently, Grützmacher and co-workers succeeded in the isolation of a stable metalcoordinated aminyl radical complexes and highlighted the potential role of their application as a hydrogen-atom abstractor. [8] It was recognized that an equilibrium existed between an M(n+1) amide and M(n) aminyl through a redox procedure (Scheme 1).…”

mentioning

confidence: 99%

Copper‐Catalyzed Intermolecular Aminocyanation and Diamination of Alkenes

Zhang¹,

Pu²,

Xiong³

et al. 2013

Angew Chem Int Ed

284

101

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“…We recently developed several processes for generating various types of nitrogen‐centered radicals, which can be captured by internal olefins to give a variety of nitrogen‐containing heterocycles 6, 7, 8. Our interest in the synthesis of (±)‐serratine ( 1 b ) was therefore stimulated by the possibility that the indolizidine framework could be introduced by using a cascade of radical cyclizations starting with an amidyl radical.…”

Section: Methodsmentioning

confidence: 99%