Evolution of the vinylogous Mannich reaction as a key construction for alkaloid synthesis

The vinylogous Mannich reaction is rapidly emerging as an important process for the construction of derivatives of delta-aminocarbonyl compounds. Because the iminium and dienol components employed in this addition may be either acyclic or cyclic, a wide variety of adducts may be quickly assembled. These intermediates may then in turn be converted into a broad array of alkaloids and substituted nitrogen heterocycles. We have developed a number of variations of this reaction and have applied some of them to the concise syntheses of a number of structurally diverse and complex alkaloid natural products. Many of these results are presented in a historical context in this Account.