Adaline Mannich reaction

A total synthesis of adaline (550) has been performed (73BSB699). The vinyl ketone 547 was submitted to hetero Diels-Alder reaction with methyl vinyl ether to yield the dihydropyran derivative 548 in 60% yield. Acid hydrolysis of 548 produced the keto aldehyde 549. Finally, a Mannich reaction involving... 

Euphococcinine and adaline (333) were synthesized from a 2-cyano-6-oxazolopiperidine [699], An anion at C(2) was condensed with 3-bromo-2-methoxy-l-propene, and after elimination of cyanide, the resultant iminium ion was alkylated with either a methyl- or pentyl-Grignard reagent to form the quaternary carbon. The second ring was closed with an intramolecular Mannich reaction. 

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