Camphorsulfonic add

The plane of symmetry bisecting varenicline means that it is meso, rather than chiral. Nevertheless, in combination with a chiral additive such as tartaric acid or camphorsulfonic add (CSA), it may still be possible to achieve asymmetric induction via aminocatalysis. In such a scenario, a nucleophilic enamine formed from varenicline might be desymmetrized by selective protonation of one of the two heteroaromatic nitrogens. Alternatively, the enamine might effect asymmetric induction merely by virtue of the chiral environment resulting from the presence of either one or two chiral camphorsulfonate counterions. However, varenicline... 

C. (E)-1-Benzyl-3-(1-iodoethyUden9)piperidine (3). A 250-mL, one-necked, round-bottomed flask containing a magnetic stirring bar and a reflux condenser topped with a rubber septum inlet is flushed with argon and charged with 4.0 g (21 mmol) of alkynylamine 2, 11 g (73 mmol) of sodium iodide (Note 9), 35 mL of 37% w/w formaldehyde solution, 5.4 g (22 mmol) of camphorsulfonic add monohydrate (Note... 

The most familiar of the sulfonic adds derived from camphor is 10-camphorsulfonic add (44, Reychler s acid45). Both enantiomers are commercially available and convenient procedures exist for their preparation by sulfonation of camphor (ref 46 exemplifies the racemate, but the procedure works equally well for optically active camphor). The free acid is often applied to the resolution of basic compounds such as amines. A detailed review on the use of derivatives of this acid as auxiliaries has been given3. Esters of this add are normally obtained by the reaction of the alcohols with the sulfonyl chloride which is also commerdally available (or readily obtained by the reaction of the free acid with phosphorus pentachloride or thionyl chloride46,48). Such esters with unsaturated alcohols have been used for diastereoselective [1,2] sigma tropic rearrangements (Section D.1.6.3.3.). Allyl esters have been used for enantioselective alkylation reactions, in which camphorsulfonic acid reacts as the chiral leaving group (Section D.1.1.2.2.). 

Chiral thiols 59 were derived from 10-camphorsulfonic add by reduction of the sulfony] chloride with lithium aluminum hydride, yielding a 1 4 mixture of enrfo/exo-diastereomers, which can be separated by chromatography60. Containing a hydroxy and a thiol functionality, 59 can be used for the formation of sulfur-containing heterocycles such as oxathianes which can react with carbanions (Section D.l.3.4.4.) or form enolates (Section D. 1.5.3.4.2.1.) and can direct osmium tetroxide catalyzed dihydroxylations (Section D.4.4.). 

F1 5. Comparison of the rate/Mw relationships for spontaneous and camphorsulfonic add (500 ppm) catalyzed styrene polymerization in CSTR type reactors... 

In the carbohydrate series, acetates can be cleaved selectively in the presence of benzoates [Scheme 4.329] and p-bromobenzoates using p-toluenesulfonic acid monohydrate (1 equivalent per acetate) in dichloromethane-methanol (9 1) at 4 C in 7 h or room temperature in 24 h. No benzoyl migration is observed. The method also works in comparable yield with camphorsulfonic add although the reaction takes 2 days at 40 and 3 days at room temperature. 

Polyaniline films have not only been shown to exhibit electrochromism in the visible region, but also in the microwave and far-IR regions of the electromagnetic spectrum. A polyaniline film doped with camphorsulfonic add and incorporated into a sohd state microwave shutter demonstrated that the transmittance and reflectance of X-band microwave energy could be modulated [6]. At a wavelength of 10 GHz, the shutter could be switched between 4.8% transmission when the polymer is oxidized and 42% transmission when the polymer is neutral. When utilized in a reflective device configuration in combination with poly(diphenylamine), polyamline yields a high reflective modulation in the far-IR [119,120]. This device shows a reflectance contrast of 53% at 10.5 p,m, 28% at 16.5 p,m, and 46% at 620 nm. 

Poly(methyl mefhacrylate)/PANI salts (dopant camphorsulfonic add or phenylphosphonic acid) Raman microscopy technique showed the presence of a second passive layer formed by dopant ions released from PANI salts and different metal cations (Fe, Zn, Cu, Ni, or Pt) [64]... 

Polyvinyl butyral-co-vinyl alcohol-co-vinyl acetate/PANI salts (dopant H3PO4, camphorsulfonic acid, paro-toluenesulfonic acid, and phenylphosphonic acid) Inhibit delamination with efficiency order poro-toluenesulfonic add < camphorsulfonic add < H3PO4 < phenylphosphonic add [69]... 

---