ASYMMETRIC PHOTOADDITION OF CHIRAL ALLENES

描述：在本修订申请中，主要研究者 指出联烯的分子内光环加成反应 与烯醇和烯酮是一个强大的工具，建设 立体化学复杂的多环结构中的碳-碳键。 他报告说，他观察到的不对称诱导， 手性1，3-二取代基的光环化和光加成反应 具有烯酮的联烯，其中不对称性完全来自 丙二烯片段 他指出，根据这些结果， 该提案的主要内容是（1）碳环丙二烯-烯酮的研究， 作为分子内、不对称 光环加成（2），以发展一个详细的了解 这些转变的机制，并制定了一个范例， 立体化学的预测（3）开发一个光学家族 具有可除去的辅助取代基的活性1，3-二取代联烯， （4）对映选择性联烯烯酮的应用 光加成反应合成生物活性单宁 诃子酸 据报道，诃子酸和相关的单宁 通过抑制小牛胸腺显示出有效的抗肿瘤活性， 人结肠腺癌拓扑异构酶I

DESCRIPTION: In this revised application, the principal investigator states that the intramolecular photocycloaddition reaction of allenes with enoates and enones is a powerful tool for the construction of carbon-carbon bonds in stereochemically complex, polycyclic structures. He reports the he has observed asymmetric induction in the photocyclization and photoaddition reactions of chiral 1,3-disubstituted allenes with an enone in which asymmetry is derived exclusively from the allene fragment. He notes that on the basis of these results, the aims of this proposal are (1) examination of carbocyclic allene-enones and allene-coumarins as substrates for the intramolecular, asymmetric photocycloaddition (2) to develop a detailed understanding of the mechanism of these transformations and develop a paradigm for the prediction of stereochemistry (3) to develop a family of optically active 1,3- disubstituted allenes with removable auxiliary substituents, and (4) the application of the enantioselective allene-enone photoaddition reaction to the synthesis of the biologically active tannin chebulic acid. It is reported that chebulic acid and related tannins exhibit potent antitumerogenic activity by inhibition of calf thymus and human colon adenocarcinoma topoisomerase I.