Manganese(III) mediated radical cyclization. I. Factors affectingphenol and cyclopentanone synthesis

Peterson, J. R.; Egler, Richard S.; Horsley, D. B.; Winter, Tamara

doi:10.1016/s0040-4039(00)61821-x

Cited by 31 publications

(5 citation statements)

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“…These reactions may still be synthetically useful if the products of further oxidation are monomeric. For instance, oxidative cyclization of 45 provides 78% of methyl salicylate ( 48 ). ,, Oxidative cyclization gives radical 46 ; oxidation of 46 gives 47 , probably as a mixture of double-bond positional isomers. The unsaturated cyclic β-keto ester 47 is more acidic than 45 and is rapidly oxidized further by 2 equiv of Mn(III) to give a cyclohexadienone that tautomerizes to phenol 48 .…”

Section: Further Oxidation Of the Productmentioning

confidence: 99%

“…6- endo -Cyclization ( n = 1) to give 104 is the exclusive reaction if the proximal carbon is more highly substituted than the distal carbon. Monosubstituted alkenes give cyclohexyl radical 104 , which is oxidized further providing a general synthesis of salicylate esters (see 45 → 48 ). ,, Oxidative cyclization of 101 , n = 1, R 1 = alkyl, R 2 = alkyl or H, also proceeds exclusively 6- endo although complex mixtures are obtained from oxidation of the radical …”

Section: α-Unsubstituted β-Keto Estersmentioning

confidence: 99%

“…Oxidative cyclization of styrene 115 with Mn(OAc) 3 affords 70% of acetate 116 . The secondary benzylic radical that is formed in the cyclization is oxidized by Mn(III) to the benzylic cation, which reacts with the solvent to give 116 .…”

Section: α-Unsubstituted β-Keto Estersmentioning

confidence: 99%

“…Monosubstituted alkenes give cyclohexyl radical 104, which is oxidized further providing a general synthesis of salicylate esters (see 45 f 48). 17,21,100 Oxidative cyclization of 101, n ) 1, R 1 ) alkyl, R 2 ) alkyl or H, also proceeds exclusively 6-endo although complex mixtures are obtained from oxidation of the radical. 21 Oxidative cyclization of 105 with Mn(OAc) 3 in acetic acid in air affords 31% of 1,2-dioxin-3-ol 108.…”

Section: R-unsubstituted β-Keto Estersmentioning

confidence: 99%

“…103 Oxidative cyclization of styrene 115 with Mn(OAc) 3 affords 70% of acetate 116. 100 The secondary benzylic radical that is formed in the cyclization is oxidized by Mn(III) to the benzylic cation, which reacts with the solvent to give 116. The improved yield of 116 as compared to 42 (21%) is probably due to conjugation of the double bond to the aromatic ring.…”

Section: R-unsubstituted β-Keto Estersmentioning

confidence: 99%

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Manganese(III)-Based Oxidative Free-Radical Cyclizations

1996

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ContentsI. Introduction 339 A. Oxidative Free-Radical Cyclizations 339 B. Mn(OAc) 3 340 II. Initiation 341 A. Mechanistic Considerations 341 B. Substrates 342 C. Oxidants 342 1. Mn(III) 342 2. Ce(IV), Fe(III), V(V), etc. 343 D. Further Oxidation of the Product 344 III. Termination 345 A. Oxidation by Mn(III) 345 B. Oxidation by Cu(OAc) 2 345 C. Chlorination 346 D. Addition to Nitriles and Carbon Monoxide 346 E. Hydrogen Abstraction 347 IV. Monocyclization 347 A. Radicals Derived from Acids 348 B. Radicals Derived from β-Keto Esters and β-Diketones That Lead to Cycloalkanones 348 1. R-Unsubstituted β-Keto Esters 348 2. R-Substituted β-Keto Esters 349 3. Diketones 351 C. Radicals Derived from β-Keto Esters, β-Diketones, and Malonate Esters That Lead to Cycloalkanes 351 D. Radicals Derived from β-Keto Esters, β-Keto Amides, and Malonate Esters That Lead to Lactones and Lactams 351 E. Additions to Aromatic Rings 352 V. Tandem Cyclizations 353 A. Additions to a Double Bond and then an Arene 353 B. Additions to Two Double Bonds 354 VI. Triple and Higher Cyclizations 356 VII. Asymmetric Induction 356 VIII. Annulations 357 IX. Oxidation of Ketones 358 X. Oxidation of Enol Ethers and Enamines 359 XI. Fragmentation−Cyclizations 360 XII. Synthetic Applications 361 XIII. Acknowledgments 362 XIV. References and Notes 362Barry B. Snider is a graduate of the University of Michigan (B.S.) and Harvard University (Ph.D.). After postdoctoral training at Columbia University, he joined the faculty of Princeton University. Since 1981 he has been at Brandeis University, where he is now Professor of Chemistry. He has been an Alfred P. Sloan fellow, a Dreyfus Teacher Scholar and an ACS Cope Scholar. His research interests are in the area of synthetic methods development and natural product synthesis. Current interests include oxidative free-radical cyclizations, Lewis acid-induced and -catalyzed reactions, ene reactions, and the synthesis of guanidine-containing natural products.

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Section: Further Oxidation Of the Productmentioning

confidence: 99%

Section: α-Unsubstituted β-Keto Estersmentioning

confidence: 99%

Section: α-Unsubstituted β-Keto Estersmentioning

confidence: 99%

Section: R-unsubstituted β-Keto Estersmentioning

confidence: 99%

Section: R-unsubstituted β-Keto Estersmentioning

confidence: 99%

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Manganese(III)-Based Oxidative Free-Radical Cyclizations

1996

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Manganese(III) Acetate-Copper(II) Acetate

Snider

2001

Encyclopedia of Reagents for Organic Synthesis

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Radical Cyclization Reactions

et al. 1996

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Radical cyclization reactions are among the most powerful and versatile methods for the construction of mono‐ and polycyclic systems. The advantages these reactions offer to the synthetic organic chemist include high functional group tolerance and mild reaction conditions combined with high levels of regio‐ and stereochemistry. Furthermore, the recent progress in radical chemistry has led to the development of a broad range of very useful practical methods to conduct radical cyclization reactions. In general, radical cyclization reactions comprise three basic steps: selective radical generation, radical cyclization, and conversion of the cyclized radical to the product. For the generation of the initial radical a broad variety of suitable precursors can be employed, such as halides, thio‐ and selenoethers, alcohols, aldehydes and hydrocarbons. The cyclization step usually involves the intramolecular addition of a radical to a multiple bond. Most often carbon–carbon multiple bonds are employed; however, there are also examples known for the addition to carbon–oxygen and carbon–nitrogen bonds. Depending on the method employed, the cyclized radical is converted to the desired product by trapping with a radical scavenger, by a fragmentation reaction, or by an electron transfer reaction. The section Mechanism, Regio‐ and Stereochemistry provides an introduction to the key features of radical cyclization with a special emphasis on the factors controlling the regio‐ and stereochemistry. The section Scope and Limitations covers the different methods used to conduct radical cyclization. The basic principles of radical chemistry and general practical considerations when conducting radical cyclizations are not discussed in detail. Several excellent review articles and books dealing with these topics are available.

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Manganese(III) mediated radical cyclization. I. Factors affectingphenol and cyclopentanone synthesis

Cited by 31 publications

References 12 publications

Manganese(III)-Based Oxidative Free-Radical Cyclizations

Manganese(III)-Based Oxidative Free-Radical Cyclizations

Manganese(III) Acetate-Copper(II) Acetate

Radical Cyclization Reactions

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