Nafion as an efficient reaction medium for diastereoselective photochemical reactions

The ability of alkali ion exchanged Nafion interior to enhance the influence of chiral auxiliaries in photochemical reactions was examined with three independent asymmetric photoreactions, namely, photoisomerization of trans,trans-2,3-diphenylcyclopropane-1-carboxylic acid derivatives, electro-cyclization of 2-oxo-1,2-dihydropyridine-1-acetic acid derivatives and oxa di-π methane rearrangement of 1,2-dihydro-2,2′-dimethylnapthalenone derivatives. Chiral auxiliaries that lead to 1:1 mixture of diastereomers in organic solvents yielded products in 5-21% diastereomeric excess when the photoreactions were carried out within the nanoclusters of alkali ion exchanged Nafion. The investigated systems also serve as probes to understand the mode of distribution of guest molecules within Nafion framework upon inclusion.