Tetrahydropyridine, 2-acetyl. formation

The reaction pathway shown in Fig. 5.25 can be based on the identification of HOP as an intermediate in the formation of ATPy and on a model experiment in which 2-methyl-1-pyrroline was used instead of 1-pyrroline. 2-Acetyl-3-methyl-3,4,5,6-tetrahydropyridine (cf. Formula 5.17) was produced, i. e., a displacement of the methyl group from position 2 in the 5-ring of the starting compound to position 3 in the 6-ring of the product. This shift can only be explained by the ring enlargement mechanism (Fig. 5.25). 

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