Bis sulfon

Bis-o-quinodimethanes have also been used to functionalize [60]-fullerene by Diels Alder reaction. An example is the preparation of main-chain polymers with incorporated [60]-fullerene units [48] illustrated in Scheme 2.20. Cycloaddition of bis-diene 50 generated in situ from bis-sulfone 49 with [60]-fullerene leads to an oligomer mixture 51. Another type of functionalization is based on the... 

Triazoline imino sugar derivatives 297 that are prospective glycosidase inhibitors have been prepared as single diastereomers in high yield via an lAOC reaction of in situ generated azido alkene 296 (Eq. 32) [78]. m-CPBA oxidation of the dithioacetal groups in the 0-acetylated 5-azido-5-deoxydibenzyl dithio-acetal of o-xylose or D-ribose 294 to the bis-sulfone 295, followed by loss of HOAc between C-1 and C-2 provided the lAOC precursor 296. 

In the tris-pentafluorophenyl analog (TFPC), in contrast to other Co corroles, aromatic amines can substitute PPh3 to form six-coordinate trivalent bis(amine) complexes.788 Bis-chlorosulfon-ation of TFPC occurs regioselectively to give the 2,17-(pyrrole)-bis-chlorosulfonated derivative fully characterized as its triphenylphosphinecobalt(III) complex.789 The amphiphilic bis-sulfonic acid was also obtained. 

Treatment with additional ligands like CN leads to monomeric complexes. Reaction of dimeric bis [/i-(2-mercaptoethyl)(2-mercaptoethyl)methylaminato]nickel(II) with either 02 or H202 leads to the formation of a dimeric product, bis [/u-(2-sulfinatoethyl)(2-mercaptoethyl)methylaminato (2-)]nickel(II). The reaction is first order in [Ni] and proceeds at a very slow rate at 40 °C (L/2 = 7.8 days k= 1.0 x 10 6s under 1 atm of 02. 297 Also the monomeric species can be oxidized to the mono(sulfones).1298-1302 These /ran.v-di thiolates do not undergo successive 02 addition to yield the bis(sulfone) like in (455a), which demonstrates the deactivation of the thiolate by the trawx-sulfone.1303... 

Pritchett et al.119 found that Ti(OPr )4 did not react with the bis(sulfon-amide) ligand itself, so they postulated that a chiral ligand initially reacted with the diethylzinc and was subsequently transferred to the titanium in the next step. Based on this assumption, they presented an improved procedure for the asymmetric alkylation of aldehyde to overcome the poor solubility of the li-... 

Water-soluble PPEs have been made by the suitable choice of ionic and highly hydrophilic side chains. These PPEs will play a role in bio-type sensing applications (vide infra). A clever example is Schanze s synthesis of a sulfonato-substituted PPE [40, 41]. The NaOH-promoted reaction of [1, 2]oxathiolane-2,2-dioxide with 2,5-diiodohydroquinone gives a bis-sulfonate that can be coupled (Pd-catalyzed) to 1,4-diethynylbenzene to form a water-soluble PPE (Scheme 4) Table 6, entry 1). In a similar approach, Schanze et al. [42] made a... 

An alternative synthesis of corannulene, also involving a pyrolysis, was reported by Siegel and co-workers (Scheme 4), The tetrabromide may be directly pyro-lyzed to corannulene, or it may be converted to a bis-sulfone where extrusion of SO2 produces a mixture of 8 along with its di- and tetrahydro derivatives, and 5,6-dimethy 1-benzo [g/ir] fluoranthene. 

The oxidation of dihetarylethene 44 with m-chloroper-benzoic acid (m-CPBA) in CH2CI2 afforded 1,1-dioxide 67 (06T5855, 073173, 08CC4622, 09JMC97) in yields up to 90% in the case of the 6-acetyl derivative, the yield of bis-sulfone 68 was only 35% (06T5855) because of a Baeyer-ViUiger oxidation side reaction of the carbonyl group. Protection of the latter as the dioxolane derivative made it possible to increase the yield of 69 to 72% (Scheme 21). 

Diols can also be deoxygenated via bis-sulfonate esters using sodium naphthale-nide.212 Cyclic sulfate esters are also cleanly reduced by lithium naphthalenide.213 214... 

Dithiocane (383 b.p. 45°C/0.1 mmHg) can be prepared in low yield by the high dilution condensation of propane-1,3-dithiol with 1,3-dibromopropane (34JA2177,62JA4075). It gives a bis-sulfone (384 m.p. 259 °C) with hydrogen peroxide. 

Table 4.3 gives some examples of the dehydrative alkylation-annulation of bis-sulfones. 

The loss of stereospecificity in the addition of bis(sulfone) anions to cyclohexenyl allylic acetates was attributed to a scrambling of the stereochemistry of the starting acetate. The ability of Pd° catalyst to effect this epimerization was confirmed in the absence of added nucleophile. This epimerization was attributed to the ability of the acetate to return to add to the ir-allyl complex via attack at the metal center (equation 177).167 This suggestion was confirmed by treatment of a preformed allylpalladium acetate dimer with CO, which resulted in cis migration of the acetate from Pd to the allyl ligand (equation 178).164... 

The final example in this section features a rare instance where the electrophilic center is s -hybridized carbon, as most cyclative cleavages involve the attack of carbonyl derivatives. Oxazolidinones are formed cyclatively18 by the displacement of a sulfonate ester by an acylsulfonamide (Fig. 5). In a variant19 of this cyclization, a quasi-meso bis-sulfonate partitions into a pair of quasi-enantiomeric sulfonates, one resin bound and the other cleaved, depending on the direction of intramolecular cyclization. The resin-bound enantiomer can then be displaced by an external nucleophile. 

An example of an er-fluorosulfonic acid ester is provided in the same scheme. Lastly, there is a comparison of a bis-sulfone and the carbanion formed by deprotonation. Note the significant shielding of the fluorine substituent in the carbanion. 

Dianions of alkyl-substituted sulfoxonium ylides 91a,b,e,f were prepared from 83 also by a two-step procedure via 2,4-dialkylated disulfones 90a-g. Deprotonation of 83 and alkylation yielded a family of bis-sulfones 90a-g, which upon a second deprotonation by treatment with an appropriate base were converted into the corresponding salts 91a,b,e,f (Scheme 11) <1996CB161>. 

C2 symmetric, chiral ketene dithioacetals containing the binaphthyl moiety can be prepared by Peterson alkenation of the title reagent (eq 6). The corresponding bis-sulfone affords one exo and one endo adduct with cyclopentadiene (eq 7) which, once separated and desulfonylated, give the corresponding norbomenes (see 1,1 -Bis(phenylsulfonyl)ethylene) ... 

A more extensive study was conducted with methallyltributylstannane the results are shown in Sch. 43. Here the promise shown by the catalyst prepared from the bis-sulfonamide was not fulfilled. This screening involved all the ligands shown in Sch. 42 and reaction temperatures of 10 and -78 °C. Here both the BINOL and bis-sulfon-amide ligands were found to be ineffectual and the best ligand was TADDOL with 1-naphthyl substituents, although poor induction was achieved with the catalyst prepared from this ligand. 

When considering sugar ring unsaturation removed from the 1,2 position, many methods are available in addition to methods analogous to those used in glycal formation. As shown in Scheme 6.39, the direct elimination of sulfonates under basic conditions provides a useful strategy [20]. Moreover, in the case of m/i5 -2,3-bis-sulfonates, initial displacement of one sulfonate with lithium iodide can be followed by metallation and tandem elimination, as shown in Scheme 6.40 [69]. 

The elimination of bis-sulfonates, described in the context of 2,3-unsaturated sugars (Scheme 6.40), was adapted to the formation of 3,4-unsaturated sugars [73]. In addition to this method, the direct conversion of vicinal hydroxyl groups was applied to a derivative of mannose. As shown in... 

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