Sodium benzenesulfinate, reaction with

The reaction of a-bromo or a-iodonitroalkanes with sodium benzenesulfinate gives a-nitro sulfones in 85-95% yields (Eq. 5.73), which proceeds via SRN1 reaction (Section 5.4).117... 

Due to the importance of this heterocycle in medicinal chemistry, solid-phase synthesis of derivatives based on this condensation reaction have been investigated. The first report in this area uses a sodium benzenesulfinate resin 247 and gives access in five steps and good overall yields to a library of imidazo[l,2- ]pyridines 248 functionalized at C-2 with an enone moiety <2002OL3935>. Later on, the preparation of libraries of compounds related to 250 or 251 from Rink amide resin 249 have been published (Scheme 68) <2003TL6265>. 

Evidence for a Michael addition of a nucleophile to alkenyl(phenyl)iodonium salts at the Cp atom has now been reported for the first time. Nucleophilic vinylic substitutions of (Z)-(/3-bromoalkenyl)iodonium tetrafiuoroborates (161) and its (Z)-(/3-chloroalkenyl) analogue with sodium benzenesulfinate in THE afforded stereoselectively (Z)-l,2-bis(benzenesulfonyl)alkene (163) with retention of configuration. Intermediate formation of (Z)-[/3-(benzenesulfonyl)alkenyl]iodonium salt (162) in these reactions was established by NMR experiments in CDCI3. The formation of (Z)-(162) involves a hitherto unobserved Michael addition of benzenesulfinate anion to the alkenyliodonium salts at the Cp atom, followed by halogen extrusion. ... 

Sulfonylation of aromatic hydrocarbons in the presence of a Lewis acid and the reaction of sodium benzenesulfinate with alkyl halides proved to be particularly easy and useful to prepare starting materials for the Julia olefination procedure (see Section 4.3.2). 

Likewise, the sulfonylhydrazones 337a-c prepared from reactions of sodium benzenesulfinate with hydrazonoyl chlorides 20a-c in ethanol at room temperature cyclized in situ to give 338a, 338b, and 339, respectively (87MI1). 

The selenonium salts 9 and 11 were found to react with one equivalent of sodium benzenesulfinate in an alcohol giving the products shown together with their ratio in Scheme 3. It is evident from the above data that the reaction of 9 and 11 with sodium benzenesulfinate gave (Z)-alkoxyvinyl sulfone 17a and the reactions at room temperature or at 60 °C afforded (Z)-bis-(phenylsulfonyl) styrene (18) as a by-product. In contrast, the reactions of salts 9 and 11 with benze-nesulfinic acid in isopropanol afforded (Z)-()5-phenylsulfonyl)vinylselenonium salts 19 and 20 in yields of 76 and 72%, respectively (Eq. 3). Neither the sulfone 17c nor the vinylsulfone 18 was isolated from these reactions [11a]. 

It is interesting to note that the cyclic salt 12 did not react with benzenesul-finic acid however, when treated with sodium benzenesulfinate in an alcohol, it gave dibenzoselenophene 21 and Z-alkoxyvinylsulfones 17a-c in moderate yields (51-77%). When the reaction was carried out in t-butyl alcohol, bis(phenylsulfonylvinyl)ether (22) was formed in 30% yield (Eq. 4). 

This reaction was carried out on cyclic and acyclic allylic carbonates. The 5-allylic thiocarbamate products were hydrolyzed to the corresponding thiol or reacted with 2-chloropyrimidine in the presence of potassium hydroxide to provide the sulfide without any loss in stereochemical purity for either example. a-Acetoxysulfones can be regarded as acid-stable, but base-labile, chiral aldehyde equivalents. These can be accessed through the palladium(0)-cataly zed reaction of geminal esters with sodium benzenesulfinate under phase-transfer conditions (eq 12). ... 

Alkyl phenyl sulfones (piCj,27) are nearly as acidic as esters hence they are readily deprotonated by n-BuLi, LDA in THF, or EtMgBr in THF to give a-metalated sulfones. Their reaction with aldehydes gives a mixture of diastereomeric P-phenylsul-fone alkoxide adducts. Reductive elimination of the benzenesulfinate moiety from the adduct to produce the alkene is usually slow. To minimize side reactions, the hydroxyl group is first converted to an acetate, benzoate, mesylate, or /7-toluenesul-fonate and then treated with an excess of sodium amalgam [Na(Hg), prepared by adding small pieces of sodium to mercury] in methanol to furnish the trans-dlk n P... 

Arylsulfonyl)pyrazol-3-ones can be synthesized directly from pyrazol-3-ones or indirectly via iodomethane salts of 4-(dimethylamino)methylpyrazol-3-ones. Hellmann and Muller (65CB638) (Scheme 23) synthesized 4-(phenylsulfonyl)methyl-pyrazol-3-one 73 by treating pyrazol-3-one 70 with paraformaldehyde and sodium benzenesulfinate 72a in DMF with a catalytic amount of acetic acid. Eight years later Messinger (73AP603) reported that the reaction of A,A,A-trimethyl(3-oxopyrazol-3-yl)methanaminium iodide 74 with sodium sulfinates 72a- c in DMF afforded the corresponding 4-(arylsulfonyl)methylpyrazol-3-ones 75a-c in 82, 67 and 74% yield, respectively. 

If a compound containing an acidic CH group is treated with formaldehyde and sodium benzenesulfinate the derived (phenylsulfonyl)methyl derivative is formed e.g., indole gives a 93% yield in the following reaction 727... 

Oxazoles, Imidazoles, and Thiazoles. Resin-bound benzenesulfinic acid 52 obtained from sodium benzenesulfinate resin 43 (Scheme 12.13) could be treated with excess TEA and aldehyde in the presence of thiazohum catalyst to provide a-ketoamide in situ. Further reactions of the a-ketoamide with PPha/I, Lawesson s reagent, and EtOH/amine generated substituted oxazoles 56, imidazoles 57, and thiazoles 58 (Scheme 12.14). 

---