Manganese(III) Acetate-Induced Formation of a Fused, Chloro-Substituted β-Lactam Derivative From a Chloroacetamide

Bremner, J. B.; Jaturonrusmee, W.

doi:10.1071/ch9901461

Cited by 5 publications

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“…Oxidative cyclization of 205 with Mn(OAc) 3 in acetic acid at 100 °C gives 32% of 206 , a model for the synthesis of fredericamycin . Oxidative cyclization of chloroacetamide 207 with Mn(OAc) 3 ·2H 2 O in acetic acid at 50 °C yields 21% of β-lactam 208 which is formed by a 4- exo -cyclization …”

Section: E Additions To Aromatic Ringsmentioning

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: E Additions To Aromatic Ringsmentioning

confidence: 99%

“…98 Oxidative cyclization of chloroacetamide 207 with Mn(OAc) 3 ‚2H 2 O in acetic acid at 50 °C yields 21% of β-lactam 208 which is formed by a 4-exo-cyclization. 92…”

Section: E Additions To Aromatic Ringsmentioning

confidence: 99%

Manganese(III)-Based Oxidative Free-Radical Cyclizations

1996

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Carbon–Carbon Bond‐Forming Reactions Promoted by Trivalent Manganese

Melikyan

1996

Organic Reactions

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In the past decade, major advances in radical chemistry have been made by the use of transition metals. This field has witnessed impressive accomplishments, and tremendous potential lies ahead. There are many transition metal‐mediated methods for producing radicals, including (a) oxidation of CH bonds or unsaturated fragments by transition metals in higher oxidation states, (b) reduction of CX bonds or unsaturated moieties by transition metals in lower oxidation states, and (c) homolysis of metal–carbon σ bonds. Redox methods for generating radicals are well elaborated and utilize transition metals in different oxidation states. In the vast majority of these reactions, transient organometallic species have not been either isolated or identified. Their tentative structures have been proposed, in some cases based solely on chemical logic. Accordingly, the mechanisms of these multistep interactions have not been fully established. Particularly lacking is a clear recognition of those elementary steps that occur inside the ligand sphere of the transition metal. In comparison with traditional methods of radical generation, redox initiators demonstrate remarkable regioselectivity and are especially efficient in polyfunctional organic compounds. Furthermore, new types of radicals, inaccessible by traditional approaches, can be successfully generated. The main difference lies in the multiple roles that metal oxidants play during the reaction, namely, one‐electron transfer between proradical and transition metal to produce radical species, followed by redox interaction with intermediate adduct radicals. For this reason, metal‐mediated reactions differ significantly from those of peroxide‐ or light‐initiated processes. Trivalent manganese occupies a rather unusual place among metal oxidants in higher oxidation states and is particularly useful in this field. Numerous novel regio‐, chemo‐, and stereoselective synthetic methods have been developed in both inter‐ and intramolecular reactions, and their applicability to the construction of complex natural and biologically active compounds has been demonstrated. Despite its growing significance for synthetic chemistry, manganese(III)‐mediated reactions have not been comprehensively reviewed in recent years. The subject of this chapter is the radical carbon–carbon bond‐forming reaction induced by trivalent manganese derivatives such as Mn(OAc) 3 ,Mn(acac) 3 , and Mn(pic) 3 . It includes the oxidative generation of α‐ or α,α‐dioxoalkyl or alkyl radicals and their subsequent addition to unsaturated moieties. Both inter‐ and intramolecular processes are discussed, with special emphasis on the regio‐, chemo‐, and stereoselectivity issues, as well as natural products syntheses. A comprehensive representation of experimental data is accompanied by critical analyses to give a reader adequate ideas of the current status of this field, of what and can be achieved, of what can be anticipated in any new reaction or in any new application of a known process, and of predictions that can be made based on the collective accumulated knowledge. Discussions of oxidations of unsaturated compounds such as arenes and alkenes, of the α‐acetoxylation and α‐chlorination of ketones, and of chlorination of alkenes are beyond the scope of this review.

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