I. Foreword by E. J. Corey II Introduction by K. C. Nicolaou III. Preface IV. Explanation of the Use of Colors in the Schemes and Text V. List of Abbreviations VI. List of Named Organic Reactions (this main section includes 250 two-page entries) VII. Named Organic Reactions in Alphabetical Order VIII. Appendix: Listing of the Named Reactions by Synthetic Type and by their Utility IX. References X. Index

Strategic Applications of Named Reactions in Organic Synthesis: Background and Detailed Mechanisms

Syntheses of medium sized rings by ring expansion reactions

The reduction of [Mn(II)-salophen] derivatives [salophen = N,N ‘-ethylenebis(salicylideneaminato) dianion] led to the formation of C−C bridged dimers. Such C−C bonds function as two electron shuttles in electron-transfer reactions. The reduction of [Mn(salophen)(THF)]2 (1) and [Mn(3,5-But4salophen)(THF)]2 (3) with 2 equiv of sodium metal led to the corresponding single C−C bond bridged dimers, [Mn2(salophen2)Na2(DME)4] (5) [salophen2 = C−C bonded salophen dimer] and [Mn2(3,5-But4salophen2)Na2(DME)6] (7), respectively. Complexes 5 and 7 undergo a further two electron reduction to [Mn2(*salophen2*)Na4(DME)6] (6) [*salophen2* = C−C doubly bonded salophen dimer] and [Mn2(*3,5-But4salophen2*)Na4(DME)4] (8), respectively, both containing a double C−C bridge. The obtention of [Mn2{salophen(Me)CH2)}2Na4(DME)4] (9) from [Mn(salophen-Me2)(THF)]2 (2) strongly supports the existence of free radical precursors in the formation of C−C bonds. Complex 6 has been used as a source of four electrons in a number of reactions...

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Carbon-carbon bonds functioning as electron shuttles : the generation of electron-rich manganese(ii)-schiff base complexes and their redox chemistry

Neutral organic electron-donor 7, formally a pyridinylidene carbene dimer, effects reductive cleavage of C−O σ-bonds in acyloin derivatives Ar(CO)CRR′OX (X = OAc, OPiv, OBz, OMs) and this represents the first cleavage of C−O σ-bonds by a neutral organic electron-donor. The methodology is applicable to a large array of substrates and the reduced counterparts were isolated in good to excellent yields. For certain substrates, donor 7 behaves as a base, effecting condensation reactions with some acetate ester derivatives of acyloins, leading to butenolides. The variation in reactivity among the different substrates was rationalized.

Metal-free reductive cleavage of c-o sigma-bonds in acyloin derivatives by an organic neutral super-electron-donor

Aryl methyl ethers, methyl esters, aryl esters, and aryl sulfonates are chemoselectively deprotected under nonhydrolytic conditions by treatment with Ph(2)S(2) (0.6 equiv) and Na (1.6 equiv) in NMP under reflux or at 90 degrees C. Quantitative utilization of the 'PhS' moiety as the effective nucleophilic species represents conservation of atom economy. Other solvents such as HMPA, DMPU, DMEU, and DMF afforded comparable results. Chloro, nitro, aldehyde, alpha,alpha-diketone, and alpha,beta-unsaturated ketone functionalities remain unaffected. The deprotection was found to take place in the order aryl ester > alkyl ester > aryl alkyl ether. Substrates bearing strong electron-withdrawing groups react at a faster rate than those not having such substitution. The differences in rate of reaction has been exploited for selective deprotection for intramolecular competition. An aryl acetate/benzoate is deprotected selectively in preference to a methyl ester or aryl methyl ether. Selective deprotection of a methyl ester is observed in the presence of an aryl alkyl ether.

Diphenyl Disulfide and Sodium in NMP as an Efficient Protocol for in Situ Generation of Thiophenolate Anion: Selective Deprotection of Aryl Alkyl Ethers and Alkyl/Aryl Esters under Nonhydrolytic Conditions†,‡

R. E. Robertson

Papers

Mechanism of the acyloin condensation