Hydroxy-steroids. Part XVIII. Reactions of 17β-chloro-16α,17α-epoxy-5α-androstane and the preparation of 17β-iodo-16α,17α-epoxy-5α-androstane

Denny, W. A.; Kumar, V.; Meakins, G. D.; Pragnell, John; Wicha, J.

doi:10.1039/p19720000486

Cited by 8 publications

(3 citation statements)

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“…Unexpectedly, transformation of ketone 20 into hydrazone 22 turned out problematic ( Scheme 10 ). A side product was formed, presumably the diazinene derivative [ 18 ] 23 . The crude mixture of hydrazine derivatives was subjected to reaction with iodine [ 19 ].…”

Section: Resultsmentioning

confidence: 99%

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Studies Towards the Total Synthesis of Di- and Sesterterpenes with Dicyclopenta[a,d]cyclooctane Skeletons. Three-component Approach to the A/B Rings Building Block

Michalak

Wicha

2005

Molecules

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Sesqui- and sesterterpenes of ophiobolin and fusicoccin families are important synthetic targets because of complexity of structure and potentially useful physiological activities, including anti-tumor activity. A synthesis of versatile building blocks for these terpenoids is described. Cyclopenta[8]annulene rings system with properly dislocated substituents was constructed using as key steps ring closing metathesis reaction and Wagner - Meerwein rearrangement. Ring closing metathesis reaction leading to cyclopenta[8]annulene was studied in detail.

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Section: Resultsmentioning

confidence: 99%

“…Model experiments with easily accessible steroid epoxide were carried out ( Scheme 11 ). It was found that AlCl 3 in ether [ 18 ] gives the best results. A mixture of two products 27 and 28 was formed in ca.…”

Section: Resultsmentioning

confidence: 99%

Studies Towards the Total Synthesis of Di- and Sesterterpenes with Dicyclopenta[a,d]cyclooctane Skeletons. Three-component Approach to the A/B Rings Building Block

Michalak

Wicha

2005

Molecules

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“…However, one of the most widely studied reactions of this type is the ring opening of steroidal 16α,17α-epoxides that usually leads to 18-norsteroids with a CC double bond in ring D or C. The rearranged products are formed as a result of a Wagner–Meerwein rearrangement that involves the formation of a carbocation with a 1,2-migration of the angular C-18 methyl group to C-17. The rearrangements can be induced by either a Brønsted acid ( p -toluenesulfonic acid, HF, HClO 4 , or HCOOH) or a Lewis acid (AlCl 3 , ZnCl 2 , or BF 3 ). The use of 17β-alkyl-16α,17α-epoxides usually led to the 17α-substituted 16α-hydroxy-17β-methyl-Δ 13 -18-norsteroids.…”

Section: Introductionmentioning

confidence: 99%

Ionic Liquid-Promoted Wagner–Meerwein Rearrangement of 16α,17α-Epoxyandrostanes and 16α,17α-Epoxyestranes

et al. 2011

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Ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim](+)[PF(6)](-)) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim](+)[BF(4)](-)) were found to promote an unusual Wagner-Meerwein rearrangement of steroidal 16α,17α-epoxides leading to unnatural 13-epi-18-nor-16-one derivatives as the main products. These compounds were isolated in good to excellent yields. 16α-Hydroxy-Δ(13)-18-norsteroids, the results of the usual rearrangement, were obtained as minor components of the reaction mixtures. The ionic liquid [bmim](+)[PF(6)](-) was shown to induce C-ring aromatization of 16α,17α-epoxyestranes due to the formation of HF, the hydrolysis product of [PF(6)](-). Increasing amounts of HF and [PO(2)F(2)](-) were detected by (19)F and (31)P NMR when the ionic liquid was reused. The structures of the steroidal products, 16-oxo-18-nor-13α-steroid derivatives, 16α-hydroxy-Δ(13)-18-norsteroids, and C-aromatic compounds were determined by two-dimensional NMR techniques and high-resolution mass spectrometry (HRMS). The ionic liquids were recirculated efficiently.

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Rearrangements involving halides

Rappe

1973

PATAI'S Chemistry of Functional Groups

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Hydroxy-steroids. Part XVIII. Reactions of 17β-chloro-16α,17α-epoxy-5α-androstane and the preparation of 17β-iodo-16α,17α-epoxy-5α-androstane

Cited by 8 publications

References 1 publication

Studies Towards the Total Synthesis of Di- and Sesterterpenes with Dicyclopenta[a,d]cyclooctane Skeletons. Three-component Approach to the A/B Rings Building Block

Studies Towards the Total Synthesis of Di- and Sesterterpenes with Dicyclopenta[a,d]cyclooctane Skeletons. Three-component Approach to the A/B Rings Building Block

Ionic Liquid-Promoted Wagner–Meerwein Rearrangement of 16α,17α-Epoxyandrostanes and 16α,17α-Epoxyestranes

Rearrangements involving halides

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