Pummerer rearrangement of sulfoxide

This reagent is both a Lewis acid and a dehydrating agent. Thus it effects Pummerer rearrangement of sulfoxides and rearrangement of pinacol to pinacolone via an epoxide.2... 

The Pummerer rearrangement of sulfoxides with acid anhydrides has been extensively utilized as a method for the synthesis of a-substituted sulfides. When a,(3-unsaturated sulfoxides are used, the initial formed oxysulfonium ion may undergo two different pathways the additive Pummerer reaction or the vinylogous Pummerer reaction. The following sections will consider examples from both pathways. 

During these explorations, the Pummerer rearrangement of sulfoxide 235 was found to undergo cyclization only to the indole nitrogen to yield thioaminal 236. Protection of the indole nitrogen also did not lead to any... 

Kita et al. have reported an asymmetric Pummerer rearrangement of optically active sulphoxides, induced by ethoxy vinyl esters (EVE). In particular ethoxy vinyl acetate 50 was used to effect the Pummerer rearrangement of sulfoxides 51a-b in good yields and high enantioselectivity. 

Tanikaga, R. Yabuki, Y. Ono, N. Kaji, A. Facile Pummerer rearrangement of sulfoxide in an acetic anhydride-trifluoroacetic anhydride mixture Tetrahedron Lett. 1976, 2257-2258. 

The Pummerer rearrangement of sulfoxides to a-acyloxy sulfides, induced by TFAA, has been used as a means of converting sulfoxides to aldehydes (eq 10). ... 

New examples of application appear regularly. In the following one [248] phenylsulfenylation of nopinone (4) was followed by oxidation to the sulfoxide. Pummerer rearrangement of the latter led directly to the a-phenylthio substituted a-unsaturated ketone (6) (overall yield 94%), starting material for further elaboration of natural sesquiterpene synthesis via 4,4-disubstituted nopinones (7). 

Perfluoroalkyl-subslitilted oxirancs 13 have been converted cleanly into monothioacetals 15 by Pummerer rearrangement of / -hydroxy-/ -(pcrfluoroalkyl) sulfoxides 14.11... 

Pummerer rearrangement of this sulfoxide in acetic anhydride under reflux furnished 3,4-dihydrothiepin 45. The trithiepine 46 was obtained upon oxidation and Pummerer rearrangement of 3,4-dihydrothiepine. Alternatively, 3,4-dihydrothiepine was also obtained by the reaction of 1,2,5-trithiepine with A-chlorosuccinimide, followed by treatment with EtjN <1997JOC2432>. 

A highly stereoselective vinylogous Pummerer rearrangement of a optically active sulfoxide has been shown to proceed by a [l,4]-migration of the sulfinyl oxygen atom via an intermediate intimate ion pair (Scheme 12).16 The reaction occurs with high enantioselectivity when o-sulfinyl-substituted benzyl carbanions are treated with trimethylsilyl halides. 

Scheme 2. Chlorination and Pummerer rearrangement of neothiobinupharidine sulfoxides.

A Japanese group has reported a general oxidation method for activated and unactivated bromides in which the key step is the Pummerer rearrangement of a pyrazinyl sulfoxide (Scheme 12). ... 

---