2- Hexenal photocycloaddition reactions

As a model reaction for the phototoxic membrane damage by PHT, PHT was photolyzed with unsaturated fatty acid, undecylenic acid methyl ester, and isolated four major photoadducts (54-57) as shown in Scheme 18 [60]. PHT was also irradiated with 1-hexene as a reference reaction [32]. Photoreactions occur through the [2+2] photocycloaddition reaction between double bonds of olefins and C1-C2, C3-C4, and C5-C6 triple bonds of PHT. These reactions most likely result from the cumulene type diradical species. 

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