Miscellaneous rearrangements

Miscellaneous PTC Reactions The field of PTC is constantly expanding toward the discovery of new enantioselective transformations. Indeed, more recent applications have demonstrated the capacity of chiral quaternary ammonium salts to catalyze a number of transformations, including the Neber rearrangement (Scheme 11.19a), ° the trifluoromethylation of carbonyl compounds (Scheme 11.19b), ° the Mannich reaction (Scheme 11.19c), and the nucleophilic aromatic substitution (SnAt)... 

Miscellaneous The treatment of allyl 1-bromo-2-naphthyl ether 43 with f-BuLi affords benzyl alcohol 44 via a sequential reaction consisting of bromine-lithium exchange, and anion translocation, followed by a [1,2]-Wittig rearrangement (equation 23). ... 

Miscellaneous reactions. Pyrrolo-benzazepinedione 50 has been synthesized by a Schmidt type rearrangement and ring enlargement of diketone 49... 

Thioxo-1,2,4-dithiazolidines can be obtained from thioxo-l,2,4-thiadiazolidines by Dimroth rearrangement (Scheme 47) or reversibly by addition and elimination of acetone (Scheme 22). 1,2,4-Dithiazole type products are also obtained from thiocarbonyl isothiocyanates (154) by reaction with CI2 <84CHEC-I(6)897>, PhMgBr, Sj, or CS2. Other routes include reactions of carbonyl isothiocyanates and thiocarbonyl isocyanates with P4S10 or Sg <84Chec-I(6)897> and sulfonyl isocyanates with dialkyl thioketenes. Phenylisothiocyanate heated with N,C-disubstituted oxaziridines affords 3,5-diimino-l,2,4-dithiazolidines (226, 227). Other miscellaneous syntheses of 1,2,4-dithiazoline derivatives include cyclization of A7-thioacyl hexafluoroacetonimine to 5,5-bis(trifluoromethyl)-... 

The examples discussed in this subsection are miscellaneous reactions which are initiated by the rearrangement of cyclobutylmethyl cations to cyclopentyl cations, and are then followed by further bond migrations to produce more stable cations. As a result, molecules with unexpected skeletal architectures are usually obtained. 

This section deals with transformations of heterocyclic rings and includes not only addition of carbenes and nitrenes, but also rearrangements frequently following these additions. Also included are topics such as the synthesis of Reissert compounds as well as miscellaneous oxidations and reductions. 

Rearrangement reactions (Miscellaneous) (see also Electrocyclic rearrangements, Sigmatropic rearrangements, Wittig rearrangement)... 

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