Cyclization of ylidenemalononitriles. 9. Rearrangement of 2-cyano-3-(1-methylcyclopentyl)indenone to 4a-methyl-9-oxo-10-cyano-1,2,3,4,4a,9-hexahydrophenanthrene

Campaigne, E.; Forsch, Ronald A.

doi:10.1021/jo00400a005

Cited by 11 publications

(1 citation statement)

References 15 publications

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“…Extension of the strategy to alkylester-containing oxonitriles 192 is less successful since competitive retro-aldol cleavage occurs with three-carbon esters (192, n = 1), whereas the alkoxide intermediates 193 from several medium-sized oxonitriles often fail to fragment because of insufficient ring strain. 99aTwo sequential ring expansions occur on exposure of the b-oxoalkenenitrile 195 to concentrated acid Scheme 42) 164. Carbonyl protonation triggers carboncarbon bond migration in 196 to generate the tertiary carbocation 197, which undergoes a second migration leading to the ring-expanded b-oxoalkenenitrile 198.Scheme 42…”

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Cyclic Oxonitriles: Synergistic Juxtaposition of Ketone and Nitrile Functionalities

Fleming¹,

Iyer²

2006

Synthesis

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Cyclic oxonitriles exhibit unusual regio-and chemoselectivities, reflecting the juxtaposition of electron-withdrawing ketone and nitrile functionalities. In this review, synthetic access to band g-oxonitriles is surveyed, as are the reactions of these two classes of oxonitriles. Collectively, the synopsis aims to highlight the synergistic properties of the nitrile and ketone groups by emphasizing synthetic applications which are otherwise difficult or impossible to perform.

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Cyclic Oxonitriles: Synergistic Juxtaposition of Ketone and Nitrile Functionalities

Fleming¹,

Iyer²

2006

Synthesis

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Addition and Substitution Reactions of Nitrile‐Stabilized Carbanions

1984

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The utilization of carbanions stabilized by various electron‐withdrawing groups to effect carboncarbon bond formation occupies a central position in organic synthesis. This chapter focuses on the reactions of nitrile‐stabilized carbanions with an array of carbon electrophiles and updates another chapter along these lines in this series. Subsequent review articles have dealt with various aspects of the chemistry of nitrile‐stabilized carbanions. In this review, the reactions of nitrile‐stabilized anions are grouped according to the nature of the substituents attached to the carbanion center bearing the nitrile group. These substituents include alkyl, alkenyl, alkynyl, and aryl groups as well as various α‐oriented halogen‐, oxygen‐, nitrogen‐, sulfur‐, and selenium‐containing groups. Notably absent from this survey are the carbanions derived from active methylene compounds bearing two electron‐withdrawing groups such as cyanoacetate esters, malononitriles, α‐sulfonylnitriles, and α‐phosphorylnitriles. Also absent are those carbanions such as Reissert compounds, which are the subject of comprehensive reviews. The chapter is arbitrarily subdivided into six sections: (1) reactions of alkyl‐, aryl‐, and heteroaryl‐substituted nitriles; (2) reactions of α,β‐ and β,γ‐unsaturated nitriles as well as tolunitriles; (3) reactions of cyanohydrins and their hydroxyl‐protected derivatives; (4) reactions of nitriles bearing α‐sulfur and α‐selenium substituents; (5) reactions of α‐(dialkylamino)nitriles; and (6) reactions of α‐halonitriles. Within each of these sections, the reactions are further subdivided according to the nature of the electrophile: (1) alkylation reactions employing alkyl halides, alkyl sulfonates, dialkyl sulfates, and epoxides; (2) arylation reactions involving the substitution of hydrogen, halogen, nitro, or alkoxy groups on aryl or heteroaryl substrates; (3) acylation reactions employing carboxylic esters, anhydrides, acid chlorides, dialkyl carbonates, and nitriles; (4) addition reactions involving aldehydes, ketones, imines, alkenes, and alkynes; and (5) Michael‐type addition reactions to unsaturated aldehydes, ketones, imines, sulfoxides, sulfones, and nitro compounds. Finally, a section involving cyclization reactions is included for each of the six groups of nitrile‐stabilized anions.

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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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Cyclization of ylidenemalononitriles. 9. Rearrangement of 2-cyano-3-(1-methylcyclopentyl)indenone to 4a-methyl-9-oxo-10-cyano-1,2,3,4,4a,9-hexahydrophenanthrene

Cited by 11 publications

References 15 publications

Cyclic Oxonitriles: Synergistic Juxtaposition of Ketone and Nitrile Functionalities

Cyclic Oxonitriles: Synergistic Juxtaposition of Ketone and Nitrile Functionalities

Addition and Substitution Reactions of Nitrile‐Stabilized Carbanions

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

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