Sulfonyl groups, migration

A heteroaromatic nucleus can serve also as an acceptor for the migrating sulfonyl group. Thus, irradiation of numerous 4-pyrimidinyl esters of alkyl and aryl sulfonic acids (24) in alcohol with low-pressure mercury arcs readily... 

In allyl sulfones 1,3-migrations of the sulfonyl group take place thermally49 51 or Pd(0)-catalyzed52 (equation 11). 

Electron-rich alkenes like an enol ether react with N-allenylsulfonamides to assist a 1,3-shift of the sulfonyl group, eventually furnishing formal [4+2]-cycloaddition products, tetrahydropyridine derivatives. The sulfonyl group migrates from the nitrogen to the central allenyl carbon atom [25b, 195]... 

Warming the dilithiate of dihenzothiazine (127) to room temperature results in [l,3]-migration of the sulfonyl group to the neighboring phenyl anion (Scheme 39) protonation of the so-formed anion provides tribenzothiazocine (102) in 88% yield <83T2073>. 

Recently, Yamamoto extended the cycloisomerization-1,3-migration approach toward the construction of indole cores possessing a C3-sulfonyl group. Thus, cydoisomerization of ortho-alkynylsulfonamides 146 occurred in the presence of Au(III)-catalyst to produce 3-sulfonylindoles 147 via a 1,3-migration of a sulfanyl group (Scheme 9.55) [216]. The proposed mechanism is similar to that reported for... 

A diastereospecific synthesis of alkenyl enolates (13) and (15) was reported as shown in Scheme 15.1 [5]. Condensation of alkenylzirconocene (8) with lithiated sulfonyloxirane (10) affords zirconate (11), which causes migration of the alkenyl group from the zirconocene into the oxirane carbon accompanied with elimination of the sulfonyl group. Thus formed intermediate (12) regiospecifically afforded the corresponding alkenyl enolates (13) or (15) depending on the substituents on the oxirane moieties. Further reactions of these alkenyl enolates (13) and (15) with aldehydes were demonstrated. 

The room temperature treatment of a series of 1-alkenyl 2-(trime-thylsilyl)ethyl sulfones leads to an intermediate o , 8-unsaturated sulfinate anion which can be methylated at sulfur to produce methyl sulfones in 54-83% (eq 12). If alkyl hydrogens are attached at a position y to the sulfonyl groups, undesirable double bond migration may occur. Although not specifically demonstrated, alkylation with other electrophiles may be possible, as shown for arenesulfinate anions. ... 

---