This contribution reviews a family of reactions devised in our laboratory that effect the oxidative conversion of phenols into 4-amido-dienones. A salient feature of this chemistry is the use of hypervalent iodine reagents, especially diacetoxyiodobenzene (DIB), as uniquely capable oxidants in the context of the new transformation. The advent of this methodology has created new opportunities in alkaloid synthesis. Our efforts toward FR-901483, TAN-1251C, cylindricine C, and other nitrogenous natural products illustrate some applications in that domain.

The oxidative cyclization of a phenolic amide to a spirolactam has long been regarded as an "impossible" reaction, because exposure of the substrates to a variety of oxidants results in formation of spirolactones with consequent loss of the amine segment. We recently communicated that this heretofore unknown transformation may be achieved by oxidation of oxazoline analogues of phenolic and indolic amides. Herein, we provide full details of our work.

A solution to the long-standing problem presented by the oxidative cyclization of a phenolic 3-arylpropionamide to a spirolactam has been developed in this laboratory via oxazoline chemistry. This research was motivated by our interest in some novel tricyclic azaspirane natural products formally derived from tyrosine, such as FR901483 and TAN1251C. In this paper, we disclose full details of the total synthesis of these substances.