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Please login to access the full content or check if you have access via Variation 3: Photolysis of Hexa-1,5-dien-3-ones

DOI: 10.1055/sos-SD-023-00535

Tidwell, T. T.Science of Synthesis, (200623583.

Photolysis of hexa-1,5-dien-3-ones results in direct cyclization to form bicyclo[2.1.1]hexan-2-ones together with (but-3-enyl)ketenes. For example, 5-methylhexa-1,5-dien-3-one (82) gives bicyclic ketone 83 (46%) together with methyl 5-methylhexanoate (85; 21%) via (3-methylbut-3-enyl)ketene (84) (Scheme 25).[‌71‌] Formation of the ketene occurs by intramolecular cyclization followed by ring opening and by α-cleavage to form a radical pair that undergoes recombination. Competition between the two pathways is controlled by the wavelength of the light and the presence of photochemical sensitizers.[‌71‌]

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