Development of palladium catalyzed-reaction and its synthetic application

由钯催化丙炔碳酸酯羰基化产生的烯丙烯酯，由于反应性的烯丙烯SP碳，提供了进一步的合成上有用的转化。为了证明烯丙烯酯的效用，我们设计了如下的多米诺骨牌型羰基化/Diels-Alder反应序列。以乙烯基代替乙炔质子的丙炔碳酸酯羰基化可得到可识别为缺电子共轭二烯的-乙烯基烯丙酯。这种α -乙烯烯丙烯酯与甲基烯醇醚作为富电子亲二烯试剂发生分子内diols - alder反应，形成独立骨架。这一有趣的合成反应被应用于维生素D_3中间体的高效构建。

An allenic ester, produced by palladium-catalyzed carbonylation of a propargylic carbonate, provides a further synthetically useful transformation because of a reactive allenic SP carbon. To demonstrate the utility of the allenic ester, we designed a following domino-type carbonylation/Diels-Alder reaction sequence. Carbonylation of a propargylic carbonate having a vinyl group in place of acetylenic proton provides an alpha-vinyl allenic ester which can be recognized as an electron-defficient conjugated diene. This alpha-vinyl allenic ester undergoes intramolecular Diels-Alder reaction with a methyl enol ether as an electron-rich dienophile, affording an indene skeleton. This synthetically interesting reaction was applied to an efficient construction of vitamin D_3 intermediate.