Isoquinolines Beckmann rearrangement-cyclization

Aromatic donble bonds may also be nsed effectively to trap the electrophilic intermediate (electrophilic aromatic snbstitntion). The Beckmann rearrangement-cyclization seqnence has fonnd ntihty in the synthesis of the isoquinoline nucleus . ... 

The Beckmann rearrangement-cyclization sequence terminated by aromatic moieties is fairly general. Recent examples of isoquinoline and dihydroisoquinoline synthesis exhibit two-step sequences using phosphorus pentachloride and phosphorus pentoxide via the cyclization of the intermediate imidoyl chlorides (equation 34). ... 

Phenethyl ketone oximes have been cyclized by a Beckmann rearrangement to isoquinolines 477 (equation 205), but quinoline derivatives 478 can also be obtained as a result of a formal displacement at the nitrogen atom of the oxime (equation 206). 

Cinnamaldoxime 65 in the presence of different H-zeolites, K-10 montmorillonite clay, amorphous SiOT-AhOa and y-alumina underwent the Beckmann rearrangement via the migration of the awft-styiyl moiety to electron-deficient nitrogen followed by an intramolecular cyclization to afford the isoquinoline 66 as the major product. Cinnamonitrile 67 and cinnamaldehyde were obtained as minor products. 

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