Reaction of 4‐hydroxy‐3‐hydroxyalkyl‐1‐methyl‐2(1H)quinolinones with Ph3P/DEAD gives either C‐ or O‐cyclized products depending on chain length. Hydroxyethyl produces only spiro cyclopropylquinolinone 6, whereas hydroxypropyl affords only pyranoquinolinone 8. Hydroxybutyl gives a 2:1 mixture of spiro cyclopentylquinolinone 11 and oxepinoquinolinone 10.
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Gary M. Coppola (2004) studied this question.