Meyer–Schuster rearrangement

The reaction proceeds 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. Formation of the unsaturated carbonyl compound is irreversible. Solvent is important and solvent caging is proposed to stabilize the transition state. ==Rupe rearrangement==

The reaction of tertiary alcohols containing an α-acetylenic group does not produce the expected aldehydes, but rather α,β-unsaturated methyl ketones via an enyne intermediate. This alternate reaction is called the Rupe reaction, and competes with the Meyer–Schuster rearrangement in the case of tertiary alcohols. ==Use of catalysts==

The traditional Meyer–Schuster rearrangement is induced by strong acids, which introduces competition with the Rupe reaction if the alcohol is tertiary. and Ag-based catalysts). Microwave-radiation with catalyst to give excellent yields with short reaction times and good stereoselectivity. ==Use in organic synthesis==

The Meyer–Schuster rearrangement has been used in several syntheses. ω-Alkynyl-ω-carbinol lactams convert into enamides using catalytic PTSA α,β-Uunsaturated thioesters have been prepared from γ-sulfur substituted propargyl alcohols. 3-Alkynyl-3-hydroxyl-1H-isoindoles rearrange under mildly acidic conditions to the α,β-unsaturated carbonyl compounds. The synthesis of a part of paclitaxel exploits this rearrangement for a diastereomerically-selective route to the E-alkene. The step shown above had a 70% yield (91% when the byproduct was converted to the Meyer-Schuster product in another step). The authors used the Meyer–Schuster rearrangement because they wanted to convert a hindered ketone to an alkene without destroying the rest of their molecule. ==History==

The reaction is named after Kurt Meyer and Kurt Schuster. Reviews have been published by Swaminathan and Narayan, ==Applications==

• Used in Butaclamol synthesis. ==References==