Wagner-Meerwein and Related Reactions

Kaneda. H. Mizuno, T. Tayoda, Y. Sakata, and S. Misumi, Bull Chem. Soc. Japan. 1974, 47. 2398. 

von Cartenn-Lichterfelde, S. Valverde, and B. Rodriguez, Austral. J. Chem.. 1974, 27, 517. 

Silver perchlorate in benzene has been used to effect rearrangement of norcaranyl methyl ethers (62) in some cases, e.g. (62 R = = H R = Me, R = H), ring- 

Tokoroyama, K. Matsuo, R. Kanazawa, H. Kotsuki, and T. Kubota, Tetrahedron Letters, 1974. 3093. C. Maignan and F, Rouessac, Bull. Soc. chim. France, 1974, 2035. 

A useful one-carbon ring-expansion reaction which has been developed involves treatment of l-(dibromomethyl)-cycloalkan-l-ols with n-butyl-lithium in hexane to give the ring-expanded ketones, usually in excellent yield e.g. l-(dibromomethyl)-cyclododecan-l-ol, which was obtained by treating cyclododecanone with dibromo-methyl-lithium, gave cyclotridecanone in 89% isolated yield.  

The epoxyamine (41) rearranges thermally to (42) rather than the predicted a-(l-aziridinyl)cyclohexyl phenyl ketone. Keto-epoxide (43) undergoes ring expansion to (44) on treatment with boron trifluoride etherate, and similarly the steroid fragments (45) and (46) give (47) and (48), respectively.  

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I. Wagner-Meerwein rearrangement and related reactions 1. Wagner-Meerwein rearrangement3b... 

In spite of the known tendency of norbornene and related systems to undergo rearrangements of the Wagner-Meerwein type during eleetro-philic addition, no such rearrangement was observed when norbornene underwent cycloaddition with the acridizinium or the. A/ -methylenium benzamide cation. As Schmidt correctly pointed out, this lack of rearrangement is an argument for a concerted reaction. Alternatively, if the cycloaddition is nonsynchronous, the time interval between step 1 and step 2 must be very short. 

The Aldol and Claisen reactions are connected with C—C bond formation. Wagner-Meerwein rearrangements are related to the generation of more stable... 

Closely related to the Wagner-Meerwein reaction is the [1,2] rearrangement of vicinal diols and related substrates collectively referred to as pinacolic rearrangements2,319. Like the Wagner-Meerwein shift, the pinacol rearrangement proceeds via formation of an intermediate cation, followed by alkyl migration and concurrent generation of a carbonyl system. 

This reaction is related to the Wagner-Meerwein Rearrangement, Demjanov Rearrangement, Tiffeneau-Demjanov Ring Expansion and Retropinacol Rearrangement involving carbocation intermediates. 

This reaction is related to the Pinacol Rearrangement and Wagner-Meerwein Rearrangement. 

Products of bromination in dimethyl sulphoxide are very similar to those of bromination in methylene chloride and indicate that in both reactions a similar ionic mechanism operates. The most interesting comparisons are the ratio of tricyclic to bicyclic components, the capture ratio of Wagner-Meerwein related pairs and the extent to which exo,cxo-2,3-disubstituted or exo,endo-2,3-disubstituted norbornanes are formed. Again some caution in analysing the results is required as product stability studies have not normally been made. 

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