Novel ene-like cycloisomerization reaction of nitrile oxides with a tethered allyltrimethylsilyl group

"I took the road less traveled by and that has made all the difference." Not only fans of the poet Robert Frost recognize the attraction of the less common reaction path. Rather than the expected [3+2] cycloaddition, a novel ene-like cycloisomerization occurs on deprotonation of allyltrimethylsilyl - oxime compounds when the β-sp² carbon atom of the allyltrimethylsilyl moiety is tethered to the oxime unit (see scheme). The resulting nitrile oxide functional group serves as an enophile, and the final cyclized product still has two functional groups suitable for further manipulations. TMS = SiMe₃.