硫縮醛 (酮) 的新形態合成方法與反應

Abstract

本篇論文圍繞在硫縮酮的新合成方法和應用。依以下三大部分作深入的探討。 首先，利用具有強給電子能力的三烷基磷配基，可以有效地活化脂肪族硫縮醛 (酮) 的碳-硫鍵。因此在適當的鎳觸媒存在下，脂肪族硫縮醛 (酮) 在不需要特別的螯合作用下，即可以與一系列的格林那試劑進行烯化反應。藉由改變起始物硫縮醛 (酮) 的取代基，或是使用不同的格林那試劑，我們能利用此烯化反應得到在有機合成上有許多應用的有機矽化合物。 第二部分是有關於碳-碳鍵的形成反應。為了改善以往在合成炔丙基硫縮酮的困難，我們嘗試利用末端炔的炔丙基硫縮酮衍生物，以偶合反應的方式來合成一系列的炔丙基硫縮酮。在研究的過程中，我們發展了一套有效的鈀催化炔丙基親核基與鹵烷的偶合反應。在鈀觸媒和三苯基磷的存在下，我們可利用炔基格林那試劑或炔基鋰和簡單的鹵烷進行偶合，而這樣的反應條件也能應用在苯基取代炔丙基硫縮酮衍生物的合成上。烷基取代的炔丙基硫縮酮衍生物，則能利用相對應的末端炔和碘烷親電基進行取代反應所獲得。 第三部分則是雙烷基取代炔丙基硫縮酮的新型態反應。我們發現在鐵觸媒和格林那試劑的存在下，利用雙烷基取代炔丙基硫縮酮和羰基化合物反應生成的beta-硫烷氧基醇，可以進行不常見的beta-氧消去反應，而得到烯炔衍生物。

The new synthetic methods and applications of dithioacetal are fully described in this thesis. Firstly, we founded that the carobn-sulfur bonds of aliphatic dithioacetals could be efficiently activated by electron-donating trialkylphosphine ligands. In the presence of suitable nickel catalyst and without the chelation effect of special designed dithioacetals, simple aliphatic dithioacetals could react with a series of Grignard reagents to give the corresponding olefinic products. By using this methodology, alkenyl silanes which have useful applications from a synthetic point of view could be easily obtained. The second part is about the carbon-carbon bond forming reaction. In order to solve the problem on the synthesis of propargylic dithioacetals, we try a new route for this synthesis by the corresponding terminal alkyne via transition-metal catalyzed cross-coupling reactions. During the study of this topic, we have developed palladium-catalyzed cross-coupling reactions of alkynyl nucleophiles and alkyl halides. In the presence of palladium catalyst and triphenylphosphine, alkynyl Grignards or alkynyllithiums could successfully couple with alkyl bromides and iodides. Aryl-substituted propargylic dithioacetals could also be obtained by this strategy. However, alkyl-substituted propargylic dithioacetals could be synthesized by the displacement reaction of the corresponding terminal alkynes with alkyl iodides. The last part is concerning the new application of dialkyl-substituted propargylic dithioacetals. The beta-thioalkoxyalcohols could be obtained in good yields by the reaction of dialkyl-substituted propargylic dithioacetals with a series of carbonyl compounds. The carbon-sulfur bond of beta-thioalkoxyalcohol can be activated in the presence of iron salt and Grignard reagent. The active intermediate is found to undergo beta-OMgI elimination and give the corresponding enyne.