The Claisen rearrangement and its applications to organic synthesis have been studied for a long time.l In recent years, this rearrangement has been applied in stereocontrolled natural product synthesis2 and asymmetric i n d ~ c t i o n . ~ The term "Claisen rearrangement", which originally denoted the rearrangement of allyl aryl ethers to 0or p-allylphenols, has now been extended to analogous ...

N-Vinyl nitrones derived from fluorenone have been prepared via a copper-mediated coupling between fluorenone oxime and vinyl boronic acids. These compounds undergo subsequent rearrangement and addition reactions that are distinct from the traditional [3 + 2] cycloaddition reactivity of nitrones. Thermal rearrangements of fluorenone N-vinyl nitrones give spiroisoxazolines, while treatment with ...

Bicyclo[3.2.0]hept-2-enes undergo thermal rearrangement to norbornenes via diradical transition structures. The synthesis of exo-7-cyclopropylbicyclo[3.2.0]hept-2-ene has been achieved by cycloaddition of cyclopentadiene and cyclopropylketene, generated by treatment of cyclopropylacetyl chloride with triethylamine. A comparison of the cyclopropyl substituent effect with that of other C7 substit...

Appending a spirocyclopropane linkage to bicyclo[3.2.0]hept-2-ene is achieved by selective kinetic cyclopropanation of 6-methylenebicyclo[3.2.0]hept-2-ene. The resultant vinylcyclobutane undergoes [1,3] migration as the dominant thermal process. A minor cyclopropylcarbinyl (CPC) rearrangement product clearly implicates a diradical transition structure. The presence and absence of other potentia...