Simultaneous Formation of More Than One Ring

Cyclization of Secondary Diphenethyl-or (Cycloalkyl)ethyl-phenethylamine Derivatives (Route B/C(a)) 

The first syntheses of the erythrinane framework reported by Belleau (81, 82) and Mondon (83-86) have been performed using cyclization of the isomeric ketalamides 151 with polyphosphoric acid via the assumed 

In this connection nonoxidative cyclization strategies are of general interest. They start also from diphenethylamines and involve a Birch 

In a new attractive B/C(a) route the required N-disubstituted amine derivatives, e.g. the metalated carboxamides 169, have been generated in situ, reacting at first the primary phenethylamins 52 or 167 with trimethylaluminum followed by the enolacetates of cyclohexanoyl carboxylic acids 168. The intermediates 169 eliminate acetic acid affording the Ai-acyliminium ions (170), which cyclize to the desired erythrinanes 68 and 96. Due to the typical H NMR shift of 14-H given (5 = 6.93 ppm (31)) the products should possess the B/C cw-configura- 

Cyclization of Tertiary Cyclohexyl-ethyl-phenethyl-amide Derivatives (Route B/C(b)) 

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