Sulfonates, photochemistry

The photochemical reaction of 2,3,4,6-tetra-0-acetyl-/3-D-gluco-pyranosyl sulfone (57) in benzene under nitrogen has been carefully studied, and a number of products identified116 (see Scheme 22). A mechanism that involves a photochemically initiated series of free-radical processes has been proposed that is consistent not only with product formation but also with the extent of incorporation of deuterium found in the various products following irradiation of 57 in benzene-d6. The mechanism shown in Scheme 22 is compatible with proposals offered to explain sulfone photochemistry in noncarbohy-... 

Another interesting example of sulfone photochemistry pertains to diyne 92, which was investigated as an early approach for the synthesis of the highly unstable nine-membered ene-diyne ring of neocarzinostatin Chrom A 1 by Wender et al. [56]. The benzophenone-sensitized desulfonation of 92 resulted in the formation of the desired, but highly unstable, compound 93 in 9-15% yield (Scheme 2.22). 

Albani, J., Vos, R., Willaert, K. and Engelborghs, Y. (1995). Interaction between human a -acid glycoprotein (orosomucoid) and 2-p-toluidinylnaphthalene-6-sulfonate. Photochemistry and... 

There are a few examples of benzylic sulfonate photochemistry that have been studied as potential photoacid generators [15]. All have electron-withdrawing groups on the benzylic ring. For instance, photolysis of the sulfonate, 94, Eq. 

The photochemistry of sulfoxides and sulfones, which was first comprehensively reviewed in 19691, continues to be an area of active research interest. In this early review some 30 to 40 primary publications on the photochemistry of sulfoxides and sulfones were described. Since that date, interest in this field has continued at a steady, rather than accelerated, pace but further reviews of the general area of photochemistry of organic sulfur compounds have appeared2,3. The present review will focus on the main areas of interest for both sulfoxides and sulfones which, in spite of their apparent similarity, exhibit quite different photochemical behavior. 

One of the major areas of interest in the photochemistry of cyclic sulfoxides has been photochemical extrusion (photodesulfurization). The general area of photoextrusion of small molecules has been comprehensively reviewed by Givens14. Although it is probably fair to point out that more photochemical studies of this type have been carried out for sulfones (q.v.) than for sulfoxides, there are now several examples in the literature of photochemical desulfinylation and these will be reviewed here. 

IV. DONOR-ACCEPTOR PROPERTIES OF SULFONES AND SULFOXIDES IN PHOTOCHEMISTRY... 

Using correspondence principles96 between photochemistry, electrochemistry and ordinary chemistry tells us that the redox properties of sulfones and sulfoxides could photochemically manifest themselves in two main directions. 

The second direction in which redox properties of sulfones and sulfoxides could manifest themselves in photochemistry is redox photosensitization108,110-114. In such a photosensitization the photosensitizer is transformed by light into a short-lived oxidant or reductant able to react with the substrate to be activated. Tazuke and Kitamura115 have discussed the parameters to play with when one... 

This review has been concerned with the photochemistry of heterocyclic systems photoreactions which are more correctly designated as reactions of functional groups have, in general, been omitted or not seriously considered. Thus, the formation of pinacols by the photoreduction of such heterocyclic ketones as 3-acetylpyridine 453 and the keto sulfone (422)454 has not been included, nor has cis-trans isomerization been reviewed. 

Stumpe and co-workers [50] have investigated the photochemistry of SCLC poly(olefin sulfone)s such as 20 and a copolymer with the same main chain but with 95% of the cinnamate groups replaced with saturated tetradecyl groups. As cast or heat-treated thin films of the polymers were irradiated at 313 nm using both nonpolarized and linearly polarized light. Initial irradiation led to an initial increase in the absorbance of the films at 280 nm followed by a decrease. The... 

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