Isopropanol photochem. addition

Not all photochemical additions take place at the carbonyl carbon. Thus photolysis of the ketone 8.215 in isopropanol in the absence of any acid gives the product of attack in the conjugate position 8.218,1185 and this is quite a common and synthetically useful pattern of behaviour.1186 It is consistent with frontier orbital control only if the reaction is not a radical coupling 8.216 + 8.217, but attack of the radical 8.217 on the ground-state a,/3-unsaturated ketone 8.215. This would be a photochemically initiated chain reaction, and should have a high quantum yield the reaction is described as being rapid . 

A new radical allylation procedure has been applied to the synthesis of a 3 -C-allyl-2, 3 -dideoxypyrimidine nucleoside, and lactone 121, made by photochemical addition of isopropanol to the corresponding 2,3-ene, has been converted to the nucleoside 122. Branched-chain sulfonates 123 have been made from 3 -ketonucleosides, and the isobutyl group was found to be superior to other possibilities, it being cleavable by iodide ion to give the sulfonic acid, an analogue of a 3 -phosphate. An ingenious route to related phosphonates is outlined in... 

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