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The Meyer–Schuster rearrangement is the chemical reaction described as an acid-catalyzed rearrangement of secondary and tertiary propargyl alcohols to α,β-unsaturated ketones if the alkyne group is internal and α,β-unsaturated aldehydes if the alkyne group is terminal.〔Meyer, K. H.; Schuster, K. ''Ber.'' 1922, ''55'', 819.()〕 Reviews have been published by Swaminathan and Narayan,〔Swaminathan, S.; Narayan, K. V. "The Rupe and Meyer-Schuster Rearrangements" ''Chem. Rev.'' 1971, ''71'', 429–438. ((Review ))〕 Vartanyan and Banbanyan,〔Vartanyan, S. A.; Banbanyan, S. O. ''Russ. Chem. Rev.'' 1967, ''36'', 670. ((Review ))〕 and Engel and Dudley,〔Engel, D.A.; Dudley, G.B. ''Organic and Biomolecular Chemistry'' 2009, ''7'', 4149–4158. ((Review ))〕 the last of which describes ways to promote the Meyer–Schuster rearrangement over other reactions available to propargyl alcohols. When catalyzed by base, the reaction is called the Favorskii reaction. ==Mechanism== The reaction mechanism〔Li, J.J. In ''Meyer-Schuster rearrangement''; Name Reactions: A Collection of Detailed Reaction Mechanisms; Springer: Berlin, 2006; pp 380–381.()〕 begins with the protonation of the alcohol which leaves in an E1 reaction to form the allene from the alkyne. Attack of a water molecule on the carbocation and deprotonation is followed by tautomerization to give the α,β-unsaturated carbonyl compound. Edens ''et al.'' have investigated the reaction mechanism.〔Edens, M.; Boerner, D.; Chase, C. R.; Nass, D.; Schiavelli, M. D. ''J. Org. Chem.'' 1977, ''42'', 3403–3408. ()〕 They found it was characterized by three major steps: (1) the rapid protonation of oxygen, (2) the slow, rate-determining step comprising the 1,3-shift of the protonated hydroxy group, and (3) the keto-enol tautomerism followed by rapid deprotonation. In a study of the rate-limiting step of the Meyer–Schuster reaction, Andres ''et al.'' showed that the driving force of the reaction is the irreversible formation of unsaturated carbonyl compounds through carbonium ions.〔Andres, J.; Cardenas, R.; Silla, E.; Tapia, O. ''J. Am. Chem. Soc.'' 1988, ''110'', 666–674. ()〕 They also found the reaction to be assisted by the solvent. This was further investigated by Tapia ''et al.'' who showed solvent caging stabilizes the transition state.〔Tapia, O.; Lluch, J.M.; Cardena, R.; Andres, J. ''J. Am. Chem. Soc.'' 1989, ''111'', 829–835. ()〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Meyer–Schuster rearrangement」の詳細全文を読む スポンサード リンク
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