COMPLEX CARBOCYCLE BY PHOTOCYCLOADDITION

点击翻译按钮获取中文摘要

The [4+4] photodimerization of 2-pyridones is as efficient method for preparing cyclooctadienes strategically functionalized for synthetic challenges such as taxol and the fusicoccanes. This single-step method for preparing complex structure from simple aromatic precursors proceeds with high region- and stereochemical control, but has not been exploited synthetically. Our studies of a previously untested intramolecular version of this reaction has laid the groundwork for applications to total synthesis. Two intramolecular approaches to taxol, and a synthesis of the complex fusicoccane are proposed. A preliminary study has demonstrated a selective intermolecular reaction of 4-alkoxy-2-pyridone with 2-pyridone, predicated on the inability to undergo [4+4] photodimerization. This new approach to control of the [4+4] reaction, in the absence of a tether, allows for other important targets to be addressed. Synthesis of the antibiotic pentalenolactone and an approach to taxol are proposed.