Synthesis and rearrangements of 2,3,4,5-tetrahydro-3-benzazocin-6(1H)ones

The preparation of 3-benzenesulfonyl- and 3-benzoyl-2,3,4,5-tetrahydro-3-benzazoein-6(1H)-ones by intramolecular acylation is described. Acid catalyzed rearrangements of these 3-benzazocin-6-ones occurs by 3,4-bond cleavage, which is followed by intramolecular or intermolecular alkylation, to produce indanones (i.e. XIV) or a 3,4-dihydroisoquinoline (II), respectively. In addition to spectral support for these structures, an independent synthesis of II is described from a known 3,4-dihydroisoquinoline. Two rearrangements of 3-benzazocin-6-ones under alkaline conditions are also described, and the products are again evidence for 3,4-bond cleavage to vinylphenones. These beuzazocine rearrangements have been observed only with the 6-keto compounds.