INTRAMOLECULAR PYRONE/PYRIDONE (4+4) PHOTOCYCLOADDITIONS

2-吡喃酮和2-吡啶酮的光化学[4+4]二聚反应是一种新的反应。 一种潜在的强有力的方法， 环辛烷。 该反应组装两个非手性的，容易制备的， 将芳香分子转化为具有四个立体异构体的1，5-环辛烯 中心和萜烯骨架。 一种前所未有的分子内反应将允许这种 第二，要有正确的认识。 元环天然产物，其中许多与 重要的生物活性（例如，抗肿瘤、抗生素等）。中 初步研究（1），具有三个原子的双吡啶酮的溶液 系链被辐照。 只有一个主要产品，来自[4+4] 观察到环化（大于80%产率，100%转化率）， 表明拴绳上的酒精强烈影响了 形成四个新的立体基因中心。 这个项目最初的目标是 项目是探索这种未经测试的分子内的范围， 反应，强调对合成重要的特征 例如系链长度和立体诱导。 的研究 [4+4]产品的化学性质， 综合，将形成调查的第二阶段。

The photochemical [4+4] dimerization of 2-pyrones and 2-pyridones is a potentially powerful method for construction of highly functionalized cyclooctanes. This reaction assembles two achiral, readily prepared, aromatic molecules into a 1,5-cyclooctadiene with four stereogenic centers and a terpene skeleton. An unprecedented intramolecular version of ths reaction would allow this transformation to be harnessed for the synthesis of complex, eight- membered ring natural products, many of which are associated with important biological activity (e.g., antitumor, antibiotic, etc.). In a preliminary study (1), a solution of a bis-pyridone with a three atom tether was irradiated. Only one major product, resulting from a [4+4] cyclization (greater than 80% yield, 100% conversion), was observed, indicating that the alcohol on the tether had strongly influenced the formation of four new stereogenic centers. The initial goal of this project is to explore the scope of this untested intramolecular reaction, emphasizing features which are important for synthetic applications such as tether length and stereoinduction. A study of the chemistry of the [4+4] product, in the context of models and total synthesis, will form the second stage of the investigation.