【作者】 宋娟；

【导师】 陆熙炎； 沈琪；

【作者基本信息】 苏州大学 ， 有机化学， 2007， 博士

【摘要】 本论文工作是在前工作的基础上,围绕着二价钯催化的反应中β-H消除的抑制及阳离子钯物种的利用两个方面展开的,结合不同的反应启动模式及淬灭方式对烯炔环化反应、烯基钯对羰基的插入反应及对α,β-不饱和羰基化合物的共轭加成做了一系列的探索。主要内容包括以下几个部分:一、Pd（OAe）₂/iminopyridine催化下氧钯化启动的炔酸烯丙酯的分子内环化在张庆海博士的工作基础上,发现了另一类可以抑制β-H消除的配体-吡啶亚胺,并且利用它顺利完成了以氧钯化启动,β-杂原子消除淬灭的烯炔分子内环化反应。研究中发现,无论是对于贫电子炔酸酯还是富电子的炔酸酯,这类亚胺配体在醋酸的反应条件下都不仅能抑制β-H的消除,同时也能稳定烯基钯中间体从而使环化反应能顺利进行。在工作中,我们还通过当量反应对它的抑制β-H消除的作用进行了验证。二、Pd（OAc）₂/bpy催化下碳钯化启动的炔酸烯丙酯的分子内环化反应以联吡啶为配体,在醋酸钯催化下,利用芳基硼酸以碳钯化的方式启动,结合β-杂原子消除的淬灭方式对分子内烯炔环化反应进行了研究。反应的最高产率为52%,在反应中存在着两个不利因素:（a）底物对碱的不稳定性与碱有利于芳基硼酸转金属化之间的矛盾;（b）体系中不易抑制的零价钯的形成。正是由于这两个不利因素使得反应的产率不能令人满意。因此,只有解决好了这两个问题反应才有希望得到所期望的结果。三、阳离子钯催化下碳钯化启动的烯基钯对碳基的加成利用双膦配体稳定的阳离子钯[dpppPd（H₂O）2]（OTf）₂实现了碳钯化启动的烯基钯对羰基的亲核加成,最高产率可达96%,并且以Pd（CF₃COO）₂/BDPP体系实现了反应的不对称催化,最高可达92%的ee值。在这个反应中底物类型和阳离子钯物种的选择是至关重要的。在同样的反应条件下,富电子的底物不能得到环化结果,而中性的醋酸钯催化剂也不能有效地催化该反应。四、Pd（OAc）₂/iminopyridine催化下芳基硼酸对α,β-不饱和羰基化合物的Michael加成反应初探以Pd（OAc）₂/iminopyridine为催化体系研究了芳基硼酸对α,β-不饱和羰基化合物的Michael加成反应,结果表明,反应体系中必须加入醋酸反应才能进行,最高产率为62%。通过已有的文献结果及实验结果比较,我们认为双氮配体的选择除了要考虑反应中抑制β-H消除的问题,同时要考虑到配体对钯中心所产生的电子效应的影响。反应中要考虑降低钯中心的电子密度即要增强钯配合物的Lewis酸性。更多还原

【Abstract】 Based on the previous work in our group, the thesis centered on the inhibition ofβ-H elimination and the use of cationic palladium complexes in Pd（Ⅱ）-catalyzed reactions. Combined the different initiation model （acetoxypalladation and carbopalladation） with different quenching methods （β-heteroatom elimination and protonolysis） , the research was focused on the reactions of carbocyclization of enyne, cyclization of aroylmethyl 2-alkynoates and Michael addition ofα,β-unsaturated carbonyl compounds. The thesis is constituted by four parts:（1） Pd（OAc）₂/iminopyridine catalyzed intermolecular carbocyclization of enyne initiated by acetoxypalladation.Based on the work of Dr. Zhang Qinghai, we disclosed another kind of ligand-iminopyridine which could help to realize the intramolecular carbocyclization of enyne initiated by acetoxypalladation. The presence of iminopyridine ligands made the Pd coordinatively saturated and theβ-hydride elimination not so feasible. Furthermore, the coordination of iminopyridine ligands to Pd increased the electron density of Pd, resulting in increasing stability of the C-Pd bond towards protonolysis. these roles had been confirmed by a stoichiometric reaction.（2） Pd（OAc）₂/bpy catalyzed intramolecular carbocyclization of enyne initiated by carbopalladation.Another sort of intramolecular carbocyclization of enyne which initiated by carbopalladation in the presence of Pd（OAc）₂ as catalyst and bipyridine as ligand was studied. The vinylpalladium intermediate was obtained by the addition of arylboronic acid to alkyne and quenched by.β-heteroatome elimination after the insertion to double bond. The reaction gave the target product in moderate yield （52%） after optimized. The reasons for unsatisfactory result were: （a） the substrate was not stable enough under the reaction condition. （b） the formation of Pd（0）. （3） Cationic paIIadium（Ⅱ）-catalyzed enantioselective cyclization of aroylmethyl 2-alkynoates.We developed a cationic palladium（Ⅱ）-catalyzed addition of vinylpalladium species to ketones under mild conditions with excellent yield （up to 96%）. The vinylpalladium intermediates was generated by the carbopalladation of alkynes triggered by the addition of arylboronic acids. Furthermore, the asymmetric version of this cascade cyclization was also realized using Pd（CF₃COO）₂/BDPP as catalyst. The ee values of the products were up to 92%. We found that the choice of substrates with electron-deficient triple bonds and cationic palladium catalysts were crucial for the reaction . This cascade reaction provided an efficient way for the construction of optically active hydroxylactones.（4） Pd（OAc）₂/iminopyridine catalyzed addition of arylboronic acid toα,β-unsaturated carbonyl compounds.The reaction gave moderate yield （62%） when Pd（OAc）₂ was used as catalyst and iminopyridine was used as ligand. The addition of acetic acid was necessary for the reaction system and the insufficient Lewis acidity of palladium complex might answer for the unsatisfactory result.更多还原