A new method for the synthesis of hydrindans was developed by the palladium mediated tandem ringexpansion and insertion reaction of alkenic cyclobutanol 5 to give the hydrindan 17 as a key step.
The iodonium ion-mediated ring expansion of olefinic cyclobutanols 20, 21, and 25 gave mixtures of iodoalkylated cyclopentanones 33a-c and 34a-c. On the other hand, the same reaction of 29, 30, and 32 stereoselectively afforded iodoalkylated cyclopentanones 33d and 33e. The stereochemical course of this reaction is also discussed.
Vinyl cyclobutanol strategy for halogenated cyclopentanoids
The iodonium ionmediatedringexpansion of the olefinic cyclobutanols 19, 20, and 22 gave the mixture of iodoalkylated cyclopentanones 27a–c and 28a–c, respectively. On the other hand, the same reaction of 24 – 26 afforded stereoselectively the iodoalkylated cyclopentanones 27d and 27e.