稀土金属有机化合物对单质硫和烯亚胺的活化

【作者】 张正星；

【导师】 周锡庚；

【作者基本信息】 复旦大学 ， 有机化学， 2010， 博士

【摘要】 小分子和有机官能团插入金属-配体键反应是许多金属促进的官能团转化反应的一个基本步骤。在过去的二十多年中,有关稀土金属有机化合物插入反应及其在有机合成和催化中应用的研究取得了令人瞩目的进展。我们课题组在这一领域进行了大量系统而卓有成效的工作,如硅酮、异(硫)氰酸酯、碳化二亚胺、烯酮、单质硫等插入稀土金属有机化合物稀土-配体键及配体杂原子-氢键的反应研究,为新型稀土衍生物的合成及其在有机合成中的应用提供了方法学支持。本论文主要研究了稀土金属有机化合物与单质硫和烯亚胺等杂丙二烯型化合物的插入反应。全文重点研究了五种类型的新反应,共合成和表征了40个新的稀土有机化合物和14个新的有机化合物,并测定了其中49个化合物的晶体结构,主要内容如下：1.研究了胍基稀土烷基化合物和芳基化合物对单质硫的活化,发现单质硫可以选择性插入[(Me3Si)2NC(NCy)2]2LnBn(Bn=CH2C6H5,Cy=c-C6H11)的Ln-C键,生成相应的苄硫基化合物{[(Me3Si)2NC(NCy)2]2Ln(μ-SBn)}2[Ln=Er (2-3-Er),Y(2-3-Y)]。该插入反应具有良好的普适性,原位形成的丁基和苯基化合物与S8反应,也能高收率的形成硫插入产物{[(Me3Si)2NC(NCy)2]2Ln(μ-SR)}2 [R=nBu,Ln=Y(2-5-Y),Er(2-5-Er)；R=Ph,Ln=Er(2-6-Er),Yb(2-6-Yb)]。但是,[(Me3Si)2NC(NCy)2]2LntBu与S8反应只能得到联硫化合物{[(Me3Si)2NC(NCy)2]2Ln}2(μ-η2:η-S2)[Ln=Er(2-4-Er),Yb(2-4-Yb)]。2-4-Er也可以由2-3-Er与S8反应生成。含胍基配体的金属烃硫基化合物迄今还未见报道,值得一提是,试图用硫醇做起始原料合成上述烃硫基化合物却没有成功,这表明利用胍基稀土烷基和芳基化合物的插入反应可以制备一些用其它方法难以合成的化合物,具有重要的研究价值和发展潜力。2.开拓性研究了二茂稀土烷基化合物和芳基化合物与烯亚胺的反应,发现室温下Ph2C=C=NtBu和PhCH=C=NtBu可以高效高选择性的插入[Cp2Ln(μMe)]2和Cp2LnPh的Ln-C键,分别生成1-氮杂烯丙基配合物Cp2Ln[tBuNC(R)CPh2](R =Me,Ln=Y(3-1-Y),Er(3-1-Er),Yb(3-1-Yb);R=Ph,Ln=Y(3-2-Y),Er (3-2-Er),Yb(3-2-Yb))和Cp2Ln[tBuNC(R)CHPh](R=Me,Ln=Y(3-3-Y),Er (3-3-Er),Yb(3-3-Yb);R=Ph,Ln=Y(3-4-Y),Er(3-4-Er),Yb(3-4-Yb))。晶体结构显示,在前者中苯基取代-1-氮杂烯丙基配体以矿η4-配位模式与金属键合,而在后者中1-氮杂烯丙基配体以η3-配位模式与金属键合,端基碳原子上的H与金属之间存在Agostic作用。所有这些为1-氮杂烯丙基配合物的合成提供了一条新路线。3.研究了烯亚胺和碳化二亚胺与二茂稀土叔丁基配合物的反应。与甲基和苯基化合物不同,可能是立体位阻大的缘故,Ph2C=C=NtBu不能直接插入二茂稀土叔丁基配合物,只能加速后者发生β-H消去反应,然后再插入所产生的Ln-H键,形成Cp2Ln[tBuNCHCPh2] (Ln=Y (4-1-Y), Er (4-1-Er))。但是,相同条件下,CyN=C=NCy与原位生成的二茂稀土叔丁基配合物反应,高收率得到CyN=C=NCy插入Ln-C(tBu)键产物Cp2Ln[(CyN)2CtBu] (Ln=Y (4-3-Y), Er(4-3-Er))。值得注意的是,位阻大的ArN=C=NAr (Ar=2,6-tPr2C6H3)也不能直接与二茂稀土叔丁基配合物反应,而只能与其分解产物[Cp2LnH]反应,生成Ln-H键插入产物Cp2Ln[(ArN)2CH] (Ln=Y (4-5-Y), Er (4-5-Er))。为了验证该机理,我们检验了[Cp2LnH]与CyN=C=NCy的反应,确实得到了预期产物Cp2Ln[(CyN)2CH] (Ln=Y (4-4-Y), Er (4-4-Er))。这些结果表明,立体因素对插入反应有重要影响。此外,烯亚胺和碳化二亚胺能插入Ln-H键系首次证实,为α-氢取代的1-氮杂烯丙基稀土配合物和甲脒基稀土配合物的合成提供了一种新方法。4.研究了1-氮杂烯丙基稀土配合物3-3-Ln和3-4-Ln与异氰酸苯酯和二氧化碳的插入反应。3-3-Ln和3-4-Ln与异氰酸苯酯反应,均生成PhNCO插入Ln-N键的产物Cp2Ln{OC[N(tBu)C(R)CHPh]NPh}(THF) (R=Me, Ln=Er (5-1-Er), Yb (5-1-Yb); R=Ph, Ln=Er (5-2-Er), Yb (5-2-Yb))。3-3-Ln与二氧化碳反应生成CO2插入Ln-N键的产物,在含HMPA的溶液中结晶得到Cp2Ln{OC[N(tBu)C(Me)CHPh]O}(HMPA) (Ln=Er (5-3-Er),Yb (5-3-Yb))。3-4-Ln与二氧化碳的反应表现出明显的金属效应,3-4-Er与CO2反应生成溶解度差的Ln-N键插入产物(Cp2Er)2{μ-η1:η1-OC[N(tBu)C(Ph)CHPh]O}2 (5-4-Er);而3-4-Yb与CO2反应生成溶解度很好的CO2插入Ln-C键产物(Cp2Yb)2{μ-η1:η2-OC[CH(Ph)C(Ph)NtBu]O}2 (5-5-Yb)。首次阐明了1-氮杂烯丙基稀土配合物具有微妙的Ln-N键和Ln-C键插入反应选择性,同时,这也为稀土有机化合物的串联插入反应设计提供了参考。5.对比研究了tBuLi促进的PhCH=C=NtBu转化反应,揭示了一系列烯亚胺新反应,为多取代环丁烯、嘧啶胺以及胺基吡喃化合物的合成提供了新方法。与稀土烷基化合物和PhCH=C=NtBu的反应不同,tBuLi和PhCH=C=NtBu并不发生直接插入反应而是先发生脱质子反应。随着反应计量比的不同,所产生的金属化氮杂丙二烯能进一步与PhCH=C=NtBu或其它不饱和基质发生多种有趣的反应。例如,tBuLi与PhCH=C=NtBu以1:1和0.5:1的计量比反应分别得到烯亚胺二聚体环丁烯亚胺双锂盐二倍体(6-1)和烯亚胺二聚体环丁烯亚胺单锂盐(6-2)。化合物6-1是苯环邻位C-H键活化的产物,能进一步和二芳基甲酮反应,经水解得到苯环邻位衍生化的2-(2-叔丁胺基-3-苯基-4-叔丁亚胺基-1-环丁烯基)苯基二芳基(Ar)甲醇(Ar=Ph,6-3;p-tolyl,6-4)。1:1计量的PhCH=C=NtBu缓慢滴加到tBuLi的已烷溶液中,进一步快速与两当量的苯甲腈反应,可以实现对反应中间体[LiC(Ph)=C=NtBu]的捕捉,生成嘧啶胺基锂盐(6-5),水解得到N-叔丁基-4-胺基-2,5,6-三苯基嘧啶(6-6)。对氯苯甲腈和间氯苯甲腈也可以发生类似的反应,得到N-叔丁基-4-胺基-2,6-二对氯苯基-5-苯基嘧啶(6-7)和N-叔丁基-4-胺基-2,6-二间氯苯基-5-苯基嘧啶(6-8)。PhCH=C=NtBu先与0.5当量的tBuLi作用,然后再与一系列的苯甲酰氯反应,分别得到多取代的胺基吡喃化合物6-9-6-13。反应中一些重要的中间体均得到实验验证。更多还原

【Abstract】 Insertion of unsaturated substrates into metal-ligand bond is a fundamental reaction in various metal-promoted functionality transformations. During the last two decades, considerable attention has been devoted to organolanthanide chemistry on exploring new insertions through choice of appropriate substrates. The related information is now being extensively used in organic synthesis and catalysis. As part of a continuing effort in our laboratory toward the development of new insertions of organolanthanide compounds and their application in organic synthesis, the present thesis investigated insertions of elemental sulfur and heteroallenes into lanthanide-ligand bond. In brief, we have developed 5 new types of reactions and synthesized 40 new organolanthanide complexes and 13 new organic compounds, among which 49 were structurally determined through X-ray single crystal diffraction analysis.1. Activation of alkyl and aryl lanthanide complexes with guanidinate coligands on elemental sulfur was studied. Sulfur atom smoothly inserted into Ln-C bond of [(Me3Si)2NC(NCy)2]2LnBn to form the corresponding thiolate complexes {[(Me3Si)2NC(NCy)2]2Ln(μ-SBn)}2 [Ln=Er (2-3-Er), Y (2-3-Y)]. Moreover, the in situ generated bis(guanidinate) lanthanide n-butyl and phenyl complexes could also react with elemental sulfur to give the insertion products {[(Me3Si)2NC(NCy)2]2Ln(μ-SR)}2 [R=nBu, Ln=Y (2-5-Y), Er (2-5-Er); R=Ph, Ln =Er (2-6-Er), Yb (2-6-Yb)] in high yields. However, only disulfide complexes {[(Me3Si)2NC(NCy)2]2Ln}2(μ-η2:η2-S2) [Ln=Er (2-4-Er), Yb (2-4-Yb)] were isolated in the reaction of [(Me3Si)2NC(NCy)2]2LntBu with S8.2-4-Er could also be prepared by reaction of 2-3-Er with S8. To the best of our knowledge, the synthesis of thiolate complexes containing guanidinate coligand has no precedent. It is noted that these thiolate and disulfide complexes would be difficult to prepare by classical metathetical reactions employing thiols as starting materials.2. Treatment of [Cp2Ln(μ-Me)]2 and Cp2LnPh with Ph2C=C=NtBu or PhCH=C=N’Bu gave the insertion products Cp2Ln[tBuNC(R’)CRPh] [R=Ph, R’= Me, Ln=Y (3-1-Y), Er (3-1-Er), Yb (3-1-Yb); R=Ph, R’=Ph, Ln=Y (3-2-Y), Er (3-2-Er), Yb (3-2-Yb); R=H, R’= Me, Ln=Y (3-3-Y), Er (3-3-Er), Yb (3-3-Yb); R =H, R’=Ph, Ln=Y (3-4-Y), Er (3-4-Er), Yb (3-4-Yb)], which represent the first example of ketenimine insertion into transition metal-carbon bond and provide an efficient method for the synthesis of organolanthanides with 1-azaallyl ligands. Furthermore, it has been found that the bonding mode of the aza-allyl to a metal depends on the natures of substituents and metals. A novelη4-bonding mode of the aryl-substituted aza-allyl to a metal is observed.3. In contrast to methyl and phenyl complexes, bis(cyclopentadienyl) lanthanide tert-butyl complexes reacted with Ph2C=C=NtBu to give the Ln-H bond insertion products Cp2Ln[tBuNCHCPh2] (Ln=Y (4-1-Y), Er (4-1-Er)), while under the same conditions bis(cyclopentadienyl) lanthanide tert-butyl complexes reacted with CyN=C=NCy to give the Ln-C(tBu) bond insertion products Cp2Ln[(CyN)2CtBu] (Ln =Y (4-3-Y), Er (4-3-Er)). It is noteworthy that reaction of huge steric 2,6-iPr2C6H3NCNC6H3iPr2-2,6 with the same complexes also afforded the Ln-H bond insertion products Cp2Ln[(ArN)2CH] (Ln=Y (4-5-Y), Er (4-5-Er)). To elucidate the probable mechanism of the formation of 4-5, we examined the reaction of [Cp2LnH] with CyN=C=NCy, wherein the expected Ln-H bond insertion products Cp2Ln[(CyN)2CH] (Ln=Y (4-4-Y), Er (4-4-Er)) were obtained. It is clear that the steric factor makes a favorable transformation of tert-butyl complexes to hydrides. To the best of our knowledge, insertions of ketenimines and carbodiimides into the Ln-H bond haven’t been reported before, which offer a new method for the synthesis of organolanthanideα-substituted 1-azaallyls and formamidinates, respectively.4.3-3-Ln and 3-4-Ln reacted with phenyl isocyanate to form the Ln-N bond insertion products Cp2Ln{OC[N(tBu)C(R)CHPh]NPh}(THF) (R=Me, Ln=Er (5-1-Er), Yb (5-1-Yb); R=Ph, Ln=Er (5-2-Er), Yb (5-2-Yb)). The reaction of 3-3-Ln and CO2 followed by crystallizing in THF in the presence of HMPA gave also the Ln-N bond insertion products Cp2Ln{OC[N(tBu)C(Me)CHPh]O}(HMPA) (Ln= Er(5-3-Er),Yb(5-3-Yb)). Metal-depended selectivity was observed in reaction of 3-4-Er and 3-4-Yb with CO2. The former gave the Ln-N bond insertion product (Cp2Er)2{μ-η1:η1-OC[N(tBu)C(Ph)CHPh]O}2 (5-4-Er), while the latter provided the Ln-C bond insertion product (Cp2Yb)2{μ-η1:η2-OC[CH(Ph)C(Ph)NtBu]O}2 (5-5-Yb). The subtle change of reactivity of 1-azaallyl lanthanide complexes described herein was not investigated before and will provide valuable information for design of new sequence insertion reactions of organolanthanide complexes.5. In contrast to the reaction of organolanthanide alkyls with PhCH=C=NtBu, it is found that treatment of PhCH=C=NtBu with tBuLi gave the H atom abstraction product other than Li-C bond insertion one. The resulting lithiated aza-allene readily reacted with PhCH=C=NtBu or other unsaturated substrates to give various interesting products depending on reaction stoichiometry. For example, the reaction oftBuLi with PhCH=C=NtBu in 1:1 or 0.5:1 provided dimeric cyclobutenimine dilithium salt (6-1) or cyclobutenimine lithium salt (6-2) respectively. Ortho-C-H bond activation of phenyl group was observed in compound 6-1 which reacted with diaryl ketone to form ortho-phenyl derivatization products 2-(2-tert-butyl-3-phenyl-4-tert-butyliminocyclobut-1-enyl)phenyl-diarylmethanol (aryl=Ph,6-3; p-tolyl,6-4). In order to capture the intermediate [LiC(Ph)=C=NtBu], the reaction of tBuLi with 1 equiv of PhCH=C=NtBu and subsequently with 2 equiv of PhCN was examined through careful control of the addition rate of PhCH=C=NtBu. Aminopyrimidine lithium salt (6-5) was obtained, which underwent hydrolysis to form N-tert-butyl-4-amino-2,5,6-triphenylpyrimidine (6-6). Similar product N-tert-butyl-4-amino-2,6-di(4-Cl-phenyl)-5-phenylpyrimidine (6-7) or N-tert-butyl-4-amino-2,6-di(3-Cl-phenyl)-5-phenylpyrimidine (6-8) was obtained when PhCN was replaced by 4-Cl-C6H4CN or 3-Cl-C6H4CN. The reaction of PhCH=C=NtBu with 0.5 equiv of tBuLi and subsequently with 0.5 equiv of various aroyl chlorides gave a series of multisubstituted aminopyrans 6-9-6-13. Some of the key intermediates in the formation process of 6-1 were successfully verified.更多还原