Synthesis of Natural Products Based on the Allene Intramolecuar Cycloaddition Stategy

分子内烯的环加成构成了步控合成各种功能化多环化合物的通用方法。特别是Diels-Alder反应充分利用了烯的独特结构，进行起来非常容易。基于这一分子内烯环加成策略，我们发展了如下几种通用的合成方法。新型多环内酯的合成。我们发现，由于其良好的几何结构，烯丙基醚极易发生分子内Diels-Alder反应。这样得到的加合物很容易通过水合氧化过程转化为相应的多环内酯。该方法成功地用于多种多环内酯的合成，并应用于去甲二萜内酯（+-）白杨苷的全合成。呋喃环转移反应。利用烯基糠基醚分子内Diels-Alder反应和碱催化的加合物开环，建立了一种新的呋喃到熔融呋喃的环转移反应。这种方法也为新一代合成多用途异苯并呋喃开辟了道路。新吲哚合成。基于烯丙二胺的分子内Diels-Alder和加合物的脱氢，我们开发了一种新的多用途吲哚合成方法。用这种方法合成了多种烷基化吲哚。并利用该方法合成了一类新的吡咯罗菲那酮碱——希帕丁。

The intramoleculat cycloadditions of allenes constitute the versatile methods for the stepreocontrolled synthesis of variously functionalized polycylic compounds. In paticular Diels-Alder reactions fully enjoyed the merits of the uique structure of allenes and proceed with extraordinary ease. On the basis of this allene intramolecular cycloaddition strategr, we have developed wvatious general systheric methods as follows.1. New polycycile Lactone Synthesis.We habe found that the allenyl ether undergoes the intramolecular Diels-Alder reaction with extraordinarty ease due to the favorable geomtry. The adducts thus obtained are easily converted into the correponing polycyclic lactones by bydratio-oxidation procedure. This method was successfully utilized in the synthesis of vasrious polycyclic lactones and spplied to the total syntersis of noreqsuiterpene lactone, (+-)platyphyllide.2. Furan Ring Transfer (FRT) Reaction.We habe developed a novel ring rtransfer reaction of furans to fused furans by virstue of a facile intramolecular Diels-Alder reaction of allenyl furfuryl ether and base-catalyzed ring opening of the resulting adduct. This method also opened the way to a new generation of syntherically versatial isobenzofurans.3. New indole Synthesis.We have developed a new versatile indole synthesis based on the intramolecular Diels-Alder of allenic dienamide and dehydrogenation of the adduct. By this method a variety of alkylated indoles were synthesized. A new class of pyrrolophenathridone alkalid, Hippadine, was also synthsized using this new methodology.