Synthesis of bridged steroids with a bicyclo [3.3.1.] nonane ring a system.

Kocor, M.; Bersz, Beata

doi:10.1016/s0040-4020(01)86794-6

Cited by 4 publications

(1 citation statement)

References 18 publications

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“…Cyclosteroids (197) and (198), from stigmasterol, and (199), from pregnenolone, are key intermediates in the synthesis of naturally occurring brassinosteroids, including brassinolide (200), teasterone (20 l), and typhasterol (202).124-127 Side-chain deuteriated derivatives of these compounds have been Cholesta-5,22E-dien-3P-o1 has been converted into 28-norbrassinolides and the related cholestanes (2O5).l3l The pregnan-21-oic acid (206), prepared from the androstane carboxylic acid (207) by a sequence starting with an Arndt-Eistert reaction, showed poor plant growth promoting 19-Hydroxycholesteryl acetate (208) reacts with lead tetraacetate and copper(I1) acetate in boiling toluene to give the diene (209) and the diacetate (210).133 These were converted into the phenol (21 1) by hydrolysis with methanolic potassium hydroxide followed by oxidation with Jones' reagent. The corresponding series of 19-nor-spirostanes can be similarly prepared from 19-hydroxydiosgenin.…”

Section: Photochemical Reactionsmentioning

confidence: 99%

Steroids: reactions and partial syntheses

Turner¹

1989

Nat. Prod. Rep.

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Section: Photochemical Reactionsmentioning

confidence: 99%

Steroids: reactions and partial syntheses

Turner¹

1989

Nat. Prod. Rep.

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The Krapcho Dealkoxycarbonylation Reaction of Esters with α‐Electron‐Withdrawing Substituents

Krapcho

Ciganek

2013

Organic Reactions

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The Krapcho reaction involves esters with α‐electron‐withdrawing substituents such as malonates, β‐keto esters, and α‐cyano esters, which undergo dealkoxycarbonylation on being heated in polar aprotic solvents (such as DMSO, DMF, or HMPT) in the presence of water, or in polar aprotic solvents with water in the presence of added salts (such as NaCN, NaCl, LiCl, LiI, or MgCl 2 ). This procedure avoids the use of strongly aqueous acidic and alkaline conditions and tolerates many functional and protecting groups. The chapter presents the mechanistic aspects of this procedure, which include reaction parameters such as solvents, salts, other additives, and the use of microwave irradiation. The diastereoselectivity of protonation of the enolate intermediate leading to the dealkoxycarbonylated products is discussed. Trapping of the intermediate enolate by electrophiles other than a proton is illustrated. Potential side reactions and same‐pot subsequent reactions of substrates are discussed along with functional‐group compatibility for halogens and nitrogen, oxygen, sulfur, selenium, and carbon functional groups. Several examples of applications of this methodology for the synthesis of natural products along with experimental conditions and procedures are presented. Closely related methods are discussed in the Comparison with Other Methods section. The tables, which consist of 371 pages, are grouped according to substrate structure. Selective entries for other methods (excluding classical aqueous acidic or basic methods) are included in the tabular survey for comparative purposes.

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ChemInform Abstract: Synthesis of Bridged Steroids with a Bicyclo(3.3.1)nonane Ring A System.

Kocor

Bersz

1987

ChemInform

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Synthesis of bridged steroids with a bicyclo [3.3.1.] nonane ring a system.

Cited by 4 publications

References 18 publications

Steroids: reactions and partial syntheses

Steroids: reactions and partial syntheses

The Krapcho Dealkoxycarbonylation Reaction of Esters with α‐Electron‐Withdrawing Substituents

ChemInform Abstract: Synthesis of Bridged Steroids with a Bicyclo(3.3.1)nonane Ring A System.

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