Spirocyclohexanone oxime

Conversion of 3-cyano-4-stilbazole (69) into a tetrahydrocopyiine derivative illustrates the use of an alkenic group as the cation precursor (Scheme 35). Such processes are frequently less clear-cut for example, reaction of either the unsaturated nitrile (70) or oxime (71) resulted in competitive cycliza-tions to the minor Ritter product (72) and the major Hoesch product (73 Scheme 36). Similar competing processes have been observed for spirocyclohexanone oximes, but in other cases no cyclic products were produced at all. ... 

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