PUMMERER Sulfoxide rearrangement

This is an example of the Pummerer sulfoxide rearrangement and is discussed (2). 

PUMMERER Sulfoxide Rearrangement Rearrangement of a sulfoxide to an a-acetoxysulfide (see 1st edition)... 

The synthesis of the benzoimidazo[l,2- ][l,2,3]thiadiazole 61 can be explained using the same mechanistic model to that used for the Hurd-Mori reaction. The amino benzimidazole 58 when treated with thionyl chloride at reflux affords the benzoimidazo[l,2-r ][l,2,3]thiadiazole 61. If, however, the reactant 58 is treated with thionyl chloride at room temperature, the chloromethyl derivative 59 is formed. This derivative was then transformed into product 61 on reflux with thionyl chloride. The proposed mechanism for the formation of product 61 is for the initial formation of the sulfoxide 60, which then undergoes a Pummerer-like rearrangement, followed by loss of SO2 and HC1 to give the c-fused 1,2,3-thiadiazole 61 (Scheme 7) <2003TL6635>. 

The one-electron oxidation of iV-benzylphenothiazine by nitric acid occurs in the presence of /i-cyclodextrin, which stabilizes the radical cation by incorporation into its cavity. The reaction is inhibited by adamantane, which preferentially occupies the cavity. Novel Pummerer-type rearrangements of / -sulfinylphenyl derivatives, yielding /7-quinones and protected dihydroquinones, and highly enantioselective Pummerer-type rearrangements of chiral, non-racemic sulfoxides have been reviewed. A comprehensive study has demonstrated that the redox potential for 7- and 8-substituted flavins is linearly correlated with Hammett a values. DFT calculations in [3.3.n]pro-pellanes highlight low ionization potentials that favour SET oxidative cleavage of the strained central C-C bond rather than direct C-H or C-C bond attack. Oxidations and reductions in water have been reviewed. ... 

Sulfoxides,5 Oxidation of sulfides to sulfoxides can be effected with CAN (2 equiv.) in CH2C12/H20 catalyzed by Bu4NBr at 25° (90-100% yields). A Pummerer-type rearrangement does not occur under these conditions. 

The Pummerer-type rearrangement of vinyl sulfoxide has been named an additive Pummerer rearrangement because both the addition to the double bond and the... 

The Pummerer Rearrangement Pummerer methyl sulfoxide rearrangement... 

Vinyl chloroformate might find interesting applications in Pummerer related rearrangements. Thus, VOC-CI reacts with sulfoxides to yield a-chlorosulfides as shown in scheme 108 (Ref. 161). In this type of reaction, VOC-Q is more... 

MCPBA AC2O, Et3N, H2O, TIFF, 28-37% yield. Subsequent use of this method has resulted in much higher yields. The deprotection proceeds by sulfoxide formation followed by a Pummer-like rearrangement to release the ketone. 

Sulfoxide derivatives can be activated by triflic anhydride and participate in a Pummerer-type rearrangement to afford benzofurans (101), benzothiophenes, or spirocyclic indolenines. ... 

Mention has already been made of attempts to obtain 2-hydroxy- and 3-hydroxypenams (compounds 301 and 303), from which penems might have been generated by loss of the elements of water. The reductive elimination performed on the 2,3-diphenylthiopenam 316 by Kametani [182], and the oxidative elimination accomplished by Hanessian on the 2-methylthio compound 298 [29], are successful examples of penem synthesis achieved from isolated penam intermediates. Other examples of this strategy involve Pummerer-type rearrangements. The preparation of penem 306 by treatment of penam sulfoxide... 

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