Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Photochemistry of Amino Ketones, 141). - Synthesis and Transannular Photocyclisation of 2-Benzoyl-1,4-bis-(tosyl)piperazines1,1-Dialkyl-1,2-bis(tosylamino)ethanes 4 are prepared in a three-step reaction starting with dialkyl ketones 1. With strong bases in dimethylformamide compounds 4 react regioselectively with 1,2-dibromoalkyl phenyl ketones 5 to afford the 2-benzoyl-1,4-bis(tosyl)piperazines 6. On irradiation (≥ 300 nm) the piperazines 6a, b, f, g, without substituents in position 6, undergo Norrish-II cleavage yielding open-chain products. Depending on the ring conformations the 2,2-dialkylpiperazines 6c, d, e form diazabicycloalkanes 10 and 11 on irradiation.
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