Chan rearrangement

The Chan rearrangement was effectively used to build up the furanoid structure on the way to taxol [123,124] (O Scheme 34). 

A new modification of the Chan rearrangement proved to be the basis of a versatile and direct strategy for iterative polyoxazole synthesis suitably exploited for the preparation of the indole-bisoxazole fragment of the complex natural product diazonamide A. Indolyloxazole... 

Other references related to the Chan rearrangement are cited in the literature. ... 

We have investigated the ferrocene/ferrocenium ion exchange to determine the effects of different solvents on electron-transfer rates. There is probably only a very small work term and very little internal rearrangement in this system. Thus the rates should reflect mostly the solvent reorganization about the reactants, the outer-sphere effect. We measured the exchange rates in a number of different solvents and did not find the dependence on the macroscopic dielectric constants predicted by the simple model [Yang, E. S. Chan, M.-S. Wahl, A. C. J. Phys. Chem. 1980, 84, 3094]. Very little difference was found for different solvents, indicating either that the formalism is incorrect or that the microscopic values of the dielectric constants are not the same as the macroscopic ones. 

Fig. 16.61 Dynamic intramolecular rearrangement of Wj(0-/-Pr) 2. [From Chisholm, M. H. Clark, D. L. Hampden-Smilh, M. J. J. Am. Chan. Soc. 15)89, III, 574-586. Reproduced wilh permission. ...

Chan FIWS, Levett G, Matthew JA (1978) Thermal isomerisation of methyl linoleate hydroperoxides. Evidence of molecular oxygen as a leaving group in a radical rearrangement. J Chem Soc Chem Commun 756-757... 

Chan has found that the reaction of 2-arsabenzenemethanol (80) with triethyl-orthoacetate gave 82 and 83107). Probable intermediate 81108) may rearrange to 82 by addition-elimination of arsabenzyl radicals, which combine to give 83. This reaction appears similar to the well-studied conversion of a-benzyloxystyrene 84 to p-phenylpropiophenone 85 109). 

CHAN Reduction of acetylenes 60 CHAPMAN Rearrangement 61 Chen 390... 

Miscellaneous Rearrangements and Bond Fission Processes - Chan and Arnold have carried out calculations to confirm that the two electrons in the biscation (145) are delocalized three-dimensionally. A review has given details of specific photoreactions of acyclic and cyclic saturated hydrocarbons that can provide paths for their functionalization. A study of the SET-induced photochemical bond fission processes in the series of 2-alkoxyphenylethers (146), (147) and (148) has been studied. The reaction involves bond cleavage in the inter-... 

Reaction with p,7-unsaturated carboxylic acids. A few years ago Dalton and Chan reported that the, 7-unsaturated carboxylic acid (1) reacts with methyllithium (2 eq.) in hexane to give the expected methyl ketone (2) and that a product (3) of rearrangement is obtained if the reaction is conducted in ether. This reaction is not connected with the cyclic structure of (1), since a... 

The naturally occurring cryptand aplasmomycin (190) is one of a unique family of ionophore antibiotics, and several syntheses of the total structure, half structure and various abbreviated segments have been published. White et al. have now described a new approach to (190) which features a novel ring contraction based on the rearrangement of a-(acyloxy) acetates originally described by Chan et al. Thus, the key intermediate (191) was treated successively with lithium diisopropylamide and trimethylsilyl triflate leading to (192) which was ultimately converted to aplasmomycin. In Corey s recent... 

Li C, Chan C, Heimann AC, Danishefsky SJ (2007) On the rearrangement of an azas-piroindolenine to a precursor to phalarine mechanistic insights. Angew Chem hit Ed 46 1444-1447... 

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