Novel Organic Syntheses by Reconstruction of Carbon Skeletons via Catalytic Carbon-Carbon Bond Cleavage

C-C键的催化裂解一直是有机和有机金属化学领域中最困难的挑战之一。这一化学最近受到了许多科学和技术的关注，并为合成有机化学打开了一个新领域的大门。下一个具有挑战性的课题是在C-C键断裂后重建新的碳骨架，从而快速、选择性地合成传统合成方法无法获得的新型有机分子。在我们最近关于Ru催化的C-C键断裂反应的报道中，首次对含β-碳消除的叔烯丙醇选择性脱烯丙基反应的机理进行了理论研究。然后，我们重点研究了环丙烯和环丁烯酮这两种适合C-C键断裂的应变有机分子的反应性。经过多次试验，我们开发了一种前所未有的具有C-C键裂解作用的Ru催化的环丙烯酮二聚反应，高产率地合成了一种新型的有机功能单体--吡喃二酮。此外，环戊二烯酮与炔烃的交叉羰化反应也得到了不对称取代的吡喃二酮类化合物。另一方面，我们还开发了新型的Ru催化环丁烯酮二聚反应合成2-吡喃酮。该反应可能是通过η4-乙烯基乙烯酮中间体进行的，该反应也被一些Rh络合物催化，然而，外部烯基取代基的立体化学完全不同于富Ru(Z)和Ru(E)催化剂的反应。

The catalytic cleavage of C-C bonds has been one of the most difficult challenges in the fields of organic and organometallic chemistry. This chemistry has recently received much scientific and technological interest, and has opened the door to a new field of synthetic organic chemistry. The next challenging subject is the reconstruction of new carbon skeletons after C-C bond cleavag, leading to the rapid and selective synthesis of novel organic molecules which can not be obtained by the simple combination of traditional synthetic methods. Among our recent reports on the ruthenium-catalyzed C-C bond cleaving reactions, the theoretical study for mechanism on the selective deallylation of tertiary homoallyl alcohols involving β-carbon elimi nation was first carried out. Then, we focused our attention on the reactivity of cyclopropenones and cyclobutenones which are the suitable strained organic molecules for C-C bond cleavage. After many trials, we developed an unprecedented ruthenium-catalvzed carbonylative dimerization of cyclopropenones involving C-C bond cleavage, which gave a novel organic functional monomer, pyranopyrandiones, in high yield. Furthermore, cross-carbonylation of cycloprorenones with alkynes was also found to give unsymmetrically substituted pyranopyrandiones. On the other hand, novel ruthenium-catalyzed dimerization of cyclobutenones to 2-pyranones has also been developed. This reaction may proceed via an η4-vinylketene intermediate, The reaction was also catalyzed by some rhodium complexes, however, the stereochemistry of the external alkenyl-substituent is totally different between the reactions using ruthenium (Z rich) and rhodium (E rich) catalysts.