Trimethylsilylcyanid als Umpolungsreagens, V. Nucleophile Acylierung von Alkylierungsmitteln mit α,β‐ungesättigten Aldehyden

Hertenstein, Ulrich; Hünig, Siegfried; Öller, Manfred

doi:10.1002/cber.19801131211

Cited by 41 publications

(2 citation statements)

References 27 publications

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“…Alternative acyl anion equivalents were also explored to circumvent the problem of allylic dithiane regioselectivity. Notably, the TMS ether of the corresponding cyanohydrin gave only α-alkylation selectivity when applied to simple model systems. Unfortunately, because of the reduced nucleophilicity of this carbanion, no alkylation product was produced when applied to the more complex and sterically hindered system 39 .…”

Section: Introductionmentioning

confidence: 78%

Concise Asymmetric Syntheses of Radicicol and Monocillin I

Garbaccio

Stachel²,

Baeschlin³

et al. 2001

J. Am. Chem. Soc.

173

114

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Radicicol (1) exhibits potent anticancer properties in vitro, which are likely to be mediated through its high affinity (20 nM) for the molecular chaperone Hsp90. Recently, we reported the results of a synthetic program targeting radicicol (1) and monocillin I (2), highlighted by the application of ring-closing metathesis to macrolide formation. These efforts resulted in a highly convergent synthesis of radicicol dimethyl ether but failed in the removal of the two aryl methyl ethers. Simple exchange of these methyl ethers with more labile functionalities disabled a key esterification in the initial route. Through extended experimentation, a successful route to both natural products was secured, along with some intriguing results that emphasize the implications of this design on a broad range of fused benzoaliphatic targets, including analogues of these natural products.

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Section: Introductionmentioning

confidence: 78%

Concise Asymmetric Syntheses of Radicicol and Monocillin I

Garbaccio

Stachel²,

Baeschlin³

et al. 2001

J. Am. Chem. Soc.

173

114

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“…Our first-generation retrosynthesis of the precursor 7 to the bicyclo[4.3.1] skeleton of the CP-molecules via a type-II intramolecular Diels−Alder (IMDA) reaction is shown in Scheme . This analysis featured a TMS−cyanohydrin coupling and a directed Aldol reaction to construct the key intermediate 7 from the simple building blocks 9 − 11 . In turn, these building blocks, in principle, could be rapidly synthesized from inexpensive, commercially available propylene glycol ( 12 ), dimethyl malonate ( 13 ), and cyclooctene ( 14 ).…”

Section: Resultsmentioning

confidence: 99%

Total Synthesis of the CP-Molecules (CP-263,114 and CP-225,917, Phomoidrides B and A). 1. Racemic and Asymmetric Synthesis of Bicyclo[4.3.1] Key Building Blocks

Nicolaou

Jung

et al. 2002

J. Am. Chem. Soc.

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A brief introduction into the chemistry of the CP-molecules is followed by first-generation synthetic sequences toward key building blocks for their total synthesis. Processes for both racemic and enantiomerically enriched bicyclo[4.3.1] ketone 6 or its equivalent are described, and the absolute stereochemistries of the optically enriched intermediates are determined. The efficient route developed to racemic 6 and the ready access to both enantiomers of key building blocks provided the opportunity for the total synthesis of the CP-molecules and determination of their absolute stereochemistry.

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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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Trimethylsilylcyanid als Umpolungsreagens, V. Nucleophile Acylierung von Alkylierungsmitteln mit α,β‐ungesättigten Aldehyden

Cited by 41 publications

References 27 publications

Concise Asymmetric Syntheses of Radicicol and Monocillin I

Concise Asymmetric Syntheses of Radicicol and Monocillin I

Total Synthesis of the CP-Molecules (CP-263,114 and CP-225,917, Phomoidrides B and A). 1. Racemic and Asymmetric Synthesis of Bicyclo[4.3.1] Key Building Blocks

Addition and Substitution Reactions of Nitrile‐Stabilized Carbanions

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