Schuster and Rupe Rearrangement

Stark and co-workers prepared novel histamine Hs-receptor antagonists with carbonyl-substituted 4-[(3-phenoxy)propyl]-1/-/-imidazole structures. The Meyer-Schuster rearrangement was used for the synthesis of one of the compounds. The p-hydroxybenzaldehyde derivative was reacted with ethynylmagnesium bromide to afford a secondary propargylic alcohol. Upon hydrolysis with 2N HCI in a refluxing ethanol/acetone mixture, the corresponding p-hydroxy cinnamaldehyde was obtained. 

In the laboratory of S.C. Welch, the Meyer-Schuster rearrangement was the key step in the stereoselective total synthesis of the antifungal mold metabolite (+)-LL-Z1271a. A tricyclic enone acetal was treated with lithium ethoxyacetylide, and the crude product was exposed to H2SO4 in anhydrous methanol, which brought about the rearrangement and afforded the desired product in 30% yield along with 12% of an epimer. 

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The products from the acid-catalyzed hydration of a-tertiary alcohols 30 (Meyer-Schuster and Rupe rearrangements) are formed via the mesomeric propargyl-allenyl cation (equation 9) and have been extensively investigated28. 

Although a variety of acid catalysts are employed in the Meyer-Schuster and Rupe rearrangements, formic acid is commonly used to effect the respective transformations. ... 

The practicality of the Meyer-Schuster and Rupe rearrangements has been further demonstrated in synthetic efforts toward insect pheremones. 

Swamlnathan, S., Narayanan, K. V. Rupe and Meyer-Schuster rearrangements. Cherm. Rev. 1971, 71,429-438. 

Andres, J., Silla, E., Tapia, O. A quantum chemical study of protonated intermediates in Rupe and Meyer-Schuster rearrangement mechanisms. THEOCHEM 1983,14, 307-314. 

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