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Debromination of 8-bromo-2′-deoxyguanosine was accomplished in high yield under neutral conditions in aqueous methanol by irradiating with visible light in the presence of methylene blue as a sensitizer and triethylamine as an electron donor. The method can be extended for the debromination of other bromoaromatic compounds.

Dithio derivatives of aldehydes and ketones have been deprotected under neutral conditions using visible light provided by a 120 Watt spotlight and methylene green as a sensitizer. The key step in the deprotection is apparently an electron transfer from the dithio derivative to the electronically excited visible dye. The resulting dithio radical cation undergoes fragmentation, and the corresponding aldehydes and ketones are isolated in excellent yields.

The Rose Bengal-induced photofragmentation of β-amino alcohols has been previously reported to proceed through a mechanism involving singlet oxygen sensitization, followed by attack of singlet oxygen and superoxide on the β-amino alcohol. An alternative mechanism involving electron transfer from the amine to the excited state Rose Bengal is supported by new evidence.

A new arylmethylsulfonyl chloride reacts with secondary or primary amines to give sulfonamides which can be photochemically cleaved, making it suitable for use as a photoremovable protecting group.

The “Photo-Birch” reduction of o-, m-, and p-xylene, using NaBH 4 , 1,3-dicyanobenzene, and photolysis, gives 1,4-dienes as products. The regioselectivity of these reactions is greatly different from the normal Birch reduction.

Summary The rate of photodechlorination of chlorobiphenyls in acetonitrile/water is dramatically enhanced when the compounds are irradiated in the presence of sodium borohydride. This rate enhancement is even larger in mi cellar solutions.