Wessely-Moser rearrangement

WESSELY - MOSER Rearrangement Acid catalyzed rearrangement d dihidroxyxanthone... 

Interconversion of ficine (4) and isoficine (5) has been carried out by refluxing in 70% HCl (3). The mechanism involved was thought to be due to a Wessely-Moser rearrangement. 

Not all of the experimental results can be explained in this way. The unexpected conversion of the ether (54) into the linear chromene (56) in fact proceeds through a base-catalyzed Wessely-Moser rearrangement of the initial product, the angular chromene (55) (71AJC2347). 

JCS(Pl)3190). This abnormal product is considered to arise from a Wessely-Moser rearrangement of the triketone (533). 

WESSELY MOSER Rearrangement 411 WESTPHALEN LETREE Rearrangement 41 West 84 Weygand 424... 

Wessely-Moser rearrangement. Rearrangement of flavones and flavanones possessing a 5-hy-droxyl group, through fission of the heterocyclic ring and reclosure of the intermediate diaroylmeth-anes in the alternate direction. 

WESSELY-MOSER Rearrangement Acid catalyzed rearrangement of dihydroxyxanthones. (see 1st edition). 

Wessely-Moser rearrangement refers to the rearrangement of benzopyran-4-ones possessing a 5-hydroxyl group, such as the demethylation product of 5,7,8-methoxyflavone 1, to yield scutellarein 2, its isomeric product. Acidic conditions are most commonly used for such transformation however, several examples of base-catalyzed reactions have also been reported. The reversibility of the rearrangement largely depends on the substituent pattern of the benzopyranone. 

Fritz Wessely and Georg H. Moser published their work on the synthesis and stmctural elucidation of scutellarein 2 in 1930 one of the key steps was the titled reaction featuring the unprecedented rearrangement from 1 to 2. This unique isomerization method soon found application in the structural elucidation of flavanoids and fruther by extension to chromones, xanthones, and their derivatives. In addition, Wessely-Moser rearrangement has been used as a surrogate of direct synthesis toward 5,6,7-substituted flavones." ... 

Since its discovery, Wessely-Moser rearrangement has been widely used in the structural elucidation of flavanones, chromones, xanthones, and their derivatives. Its popularity should be largely attributed to the fact that differentiation between a 5,7,8-arranged benzopyranone and its 5,6,7-isomer is often difficult, and sometimes impossible, by the classical techniques such as NMR studies (even with shift reagents). ... 

Research by Suschitzky et al. demonstrated that thia- and aza-version of Wessely-Moser rearrangements could be achieved under basic conditions... 

Preparation of 5,6,7-Trihydroxy-chromen-4-one 26 Via the Wessely-Moser Rearrangement of 5,7,8-Trimethoxy-chromen-4-one 25 ... 

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