| Abstract
| - Three N-alkylpyridinium photosensitizers having chiral alkyl groups have been prepared by reacting2,4,6-triphenylpyrylium tetrafluoroborate ion with (1R,2S)-(−)-norephedrine, (S)-(+)-2-(aminomethyl)pyrrolidine, and (R)-(−)-1-cyclohexylethylamine. Laser flash photolysis allows detection ofthe corresponding triplet excited states that are quenched by hydrogen atom donors and electrondonors. Asymmetric quenching of the chiral triplet excited state was observed using enantiomericallypure 1,2-diamino cyclohexane as quencher. Low enantiomeric excess values (up to 7%) weremeasured for the photochemical cyclization of 5-methyl-4-hexenoic acid to its corresponding γ-lactoneusing these chiral N-alkylpyridinium as photosensitizers.
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