2- Phenylsulfonyl-l,3-cyclohexadiene

The preparations of the starting sulfones are also given [404]. See [405] for the synthesis of 2-(phenylsulfonyl)-l,3-cyclohexadiene and related dienes. 

Fuchs recently reported an economical and environmentally friendly syntheses of 2-(phenylsulfonyl)-l,3-cyclohexadiene (30) and 2-(phenylsulfonyl)-l,3-cycloheptadienes.21 These compounds are valuable intermediates to several groups of researchers. Dehydrobromination of intermediate 29 was accomplished by Hunig s base and 5 mol% Pd catalyst in acetonitrile to yield 2-(phenylsulfonyl)-l,3-cyclohexadiene (30). 

Synthesis of 2-(Phenylsulfonyl)-l,3-Cyclohexadiene 0, E. Backvall, S. K. Juntunen, and 0. S. Andell, Department of Organic Chemistry, University of Uppsala, Box 531, S-751 21 Uppsala, Sweden... 

Preparative Methods can be prepared from the epox-idation of 2-phenylsulfonyl-l,3-cyclohexadiene using... 

Selenosulfonylation of olefins in the presence of boron trifluoride etherate produces chiefly or exclusively M products arising from a stereospecific anti addition, from which vinyl sulfones can be obtained by stereospecific oxidation-elimination with m-chloroper-benzoic acid134. When the reaction is carried out on conjugated dienes, with the exception of isoprene, M 1,2-addition products are generally formed selectively from which, through the above-reported oxidation-elimination procedure, 2-(phenylsulfonyl)-l,3-dienes may be prepared (equation 123)135. Interestingly, the selenosulfonylation of butadiene gives quantitatively the 1,4-adduct at room temperature, but selectively 1,2-adducts at 0°C. Furthermore, while the addition to cyclic 1,3-dienes, such as cyclohexadiene and cycloheptadiene, is completely anti stereospecific, the addition to 2,4-hexadienes is nonstereospecific and affords mixtures of erythro and threo isomers. For both (E,E)- and ( ,Z)-2,4-hexadienes, the threo isomer prevails if the reaction is carried out at room temperature. 

Reports on the synthesis of diene complexes using Fe2(CO)9 are more common. Reaction of 2-phenylsulfonyl-1,3-cyclohexadiene with 2equiv. of Fe2(GO)9 in refluxing ether formed the [l-(phenylsulfonyl)-l,3-cyclohexa-diene]iron(0)tricarbonyl isomer 26. The reaction is catalyzed by 1-aza-1,3-butadiene. In a separate study, 1-aza-1,3-butadienes were shown to effect a quantitative catalytic complexation of cyclohexadienes with Fe2(GO)9. Activities are greatly enhanced in the presence of aryl rings bonded to nitrogen. 

A reoxidation of the catalytic amounts of HQ to BQ in Scheme 11.13 by molecular oxygen was reahzed by the use of an oxygen-activating metal macrocyclic complex as cocatalyst [59, 68-71]. This leads to a mild biomimetic aerobic oxidation which is now based on a triple catalytic system (Scheme 11.14). With this system, 1,3-cyclohexadiene is oxidized to tranx-1,4-diacetoxy-2room temperature in 85-89% yield (>91% trans) [68]. With the use of 2-phenylsulfonyl-l,4-BQ as quinone, the trans selectivity of this process was >97% [59]. 

The DA reaction of frani-l-nitro-2-phenylsulfonylethy-lene (4a) [13] with 1,3-cyclohexadiene occurred smoothly at 60 °C to give nitro phenylsulfonyl bicyclo[2.2.2]octene 6a [14] (Table 15.1), which was then subject to desulfony-lation with DBU followed by the Barton-Zard reaction to... 

Dimethyl- and 5,5-diethyl-1,3-cyclohexadienes (49a and 49b) [50] derived from the corresponding aUylic alcohols reacted with bis(phenylsulfonyl)ethylene 4b to give bis(phe-nylsulfonyl)bicyclo[2.2.2]octenes 51a and 51b, which underwent the modified Barton-Zard reaction (CNCH2 C02Et, DBU) to afford isomerically pure dihydroisoin-dole-l-carboxylates 52a and 52b in good yields (Table 15.3) [51]. Carboxylates 52a and 52b were reduced to the corresponding alcohols by treatment with LiAlfti in THF and these alcohols were immediately subject to cyclic tetrame-rization reaction under acidic conditions [51]. Porphyrins 53a-H2 and 53b-H2 were obtained as mixtures of... 

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