Ferrocene studies III. Platinum and palladium complexes of [(dimethylamino)methyl]ferrocene

Moynahan, E. Bradley; Popp, Frank D.; Werneke, M. F.

doi:10.1016/s0022-328x(00)87779-7

Cited by 15 publications

(3 citation statements)

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“…The capability of substrates to undergo cyclopalladation showed an intriguing dependence on the nature of the palladium source, specifically the counteranion to Pd. The attempted cyclopalladation of (dimethylamino)methylferrocene with K 2 PdCl 4 resulted only in amine ligation . Shaw found in 1974 that the addition of 1 equiv of sodium acetate relative to Pd generates the desired cyclometalated product (Scheme a), an effect seen in his studies with other cyclometalations .…”

Section: Historical Background Of Chiral Carboxylate Chemistrymentioning

confidence: 98%

“…The attempted cyclopalladation of (dimethylamino)methylferrocene with K 2 PdCl 4 resulted only in amine ligation. 13 Shaw found in 1974 that the addition of 1 equiv of sodium acetate relative to Pd generates the desired cyclometalated product (Scheme 1a), 14 an effect seen in his studies with other cyclometalations. 15 Basic conditions (NaOH) without acetate resulted in only partial cyclopalladation, indicating that acetate did not merely neutralize HCl.…”

Section: Historical Background Of Chiral Carboxylate Chemistrymentioning

confidence: 99%

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From Pd(OAc)₂ to Chiral Catalysts: The Discovery and Development of Bifunctional Mono-N-Protected Amino Acid Ligands for Diverse C–H Functionalization Reactions

et al. 2020

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Metrics & MoreArticle Recommendations CONSPECTUS:The functionalization of unactivated carbon− hydrogen bonds is a transformative strategy for the rapid construction of molecular complexity given the ubiquitous presence of C−H bonds in organic molecules. It represents a powerful tool for accelerating the synthesis of natural products and bioactive compounds while reducing the environmental and economic costs of synthesis. At the same time, the ubiquity and strength of C−H bonds also present major challenges toward the realization of transformations that are both highly selective and efficient. The development of practical C−H functionalization reactions has thus remained a compelling yet elusive goal in organic chemistry for over a century. Specifically, the capability to form useful new C−C, C−N, C−O, and C−X bonds via direct C−H functionalization would have wide-ranging impacts in organic synthesis. Palladium is especially attractive as a catalyst for such C−H functionalizations because of the diverse reactivity of intermediate palladium−carbon bonds. Early efforts using cyclopalladation with Pd(OAc) 2 and related salts led to the development of many Pd-catalyzed C−H functionalization reactions. However, Pd(OAc) 2 and other simple Pd salts perform only racemic transformations, which prompted a long search for effective chiral catalysts dating back to the 1970s. Pd salts also have low reactivity with synthetically useful substrates. To address these issues, effective and reliable ligands capable of accelerating and improving the selectivity of Pd-catalyzed C−H functionalizations are needed.In this Account, we highlight the discovery and development of bifunctional mono-N-protected amino acid (MPAA) ligands, which make great strides toward addressing these two challenges. MPAAs enable numerous Pd(II)-catalyzed C(sp 2 )−H and C(sp 3 )−H functionalization reactions of synthetically relevant substrates under operationally practical conditions with excellent stereoselectivity when applicable. Mechanistic studies indicate that MPAAs operate as unique bifunctional ligands for C−H activation in which both the carboxylate and amide are coordinated to Pd. The N-acyl group plays an active role in the C−H cleavage step, greatly accelerating C−H activation. The rigid MPAA chelation also results in a predictable transfer of chiral information from a single chiral center on the ligand to the substrate and permits the development of a rational stereomodel to predict the stereochemical outcome of enantioselective reactions. We also describe the application of MPAA-enabled C−H functionalization in total synthesis and provide an outlook for future development in this area. We anticipate that MPAAs and related next-generation ligands will continue to stimulate development in the field of Pd-catalyzed C−H functionalization.

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Section: Historical Background Of Chiral Carboxylate Chemistrymentioning

confidence: 98%

Section: Historical Background Of Chiral Carboxylate Chemistrymentioning

confidence: 99%

From Pd(OAc)₂ to Chiral Catalysts: The Discovery and Development of Bifunctional Mono-N-Protected Amino Acid Ligands for Diverse C–H Functionalization Reactions

et al. 2020

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“…In one of the classic examples, the cyclopalladation of N,N-dimethylferrocenylmethylamine did not proceed in the absence of base. 26 This was surprising since the cyclopentadienyl ring within the ferrocene moiety was known to be more susceptible to electrophilic attack by the palladium center than its benzene counterpart. 27 Nonetheless, the cyclopalladated complex could be attained when sodium acetate was introduced into the reaction.…”

Section: Effects Of Bases In Cyclometalationmentioning

confidence: 99%

The chemistry of cyclometalation : a comprehensive study on cycloiridated 1-arylalkylamine and imine complexes

Chen¹

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As fundamental ligand frameworks within the field of cyclometalation, the 1arylalkylamine and imine motifs have a widespread presence as cyclometalating ligands for an extensive number of transition metal elements. In the thesis, we investigate the outcome of cycloiridation of various 1-arylalkylamine and imine ligands with [IrCp*Cl2]2. A good balance of steric factors within the organic scaffold was found to be vital for the formation and stability of amino-derived iridacycles. While excessive steric hindrance would lead to numerous side reactions affording an assortment of byproducts, the lack of steric bulk within the amine ligands would lead to an internal oxidation to its imine functionality within the cyclometalated ring. Investigations into the failed cyclization procedure revealed a consistent competing pathway leading to either a strained ring system or an iminium species. The postulated intermediates can then readily undergo hydrolysis to provide a N-dealkylated amine moiety and a carbonyl compound. Optically-active cycloiridated complexes from successful direct ortho-metalation procedures were characterized for its conformational lock and evaluated for its efficiency in the catalytic asymmetric hydrogen transfer reaction. Lastly, we examine the crystallographic structures of the synthesized iridacycles to gain insights into their bonding. III ACKNOWLEDGEMENTS As I progress to the next stage of life after Ph.D. studies, feelings of sweet and bitterness came as I recall the seven years I had (including two and a half years from my undergraduate days) in this very group. The journey has been awesome, and there are many people whom I must thank for their support and encouragements over the years. First and foremost, I would like to express my gratitude to my supervisor, Professor Leung Pak-Hing. Without his support, whether research or otherwise, I would have not come so far to where I am today. His motivation, patience and cheerfulness has kept me going strong over the ups and downs in the course of my Ph.D. studies. I also truly appreciate the scientific freedom he has granted to me, which left me with a satisfying and enriching learning experience. My gratitude also extends to my co-supervisor, Dr. Sumod A. Pullarkat, for his continual support, guidance, encouragement and patience with me throughout these years. His door was always open to us, providing much support, and the occasional chats, whenever we needed it. Your advice, whether research or otherwise, will always be invaluable to me. Next, I would like to specifically show my gratitude to Jonathan Wong, who have shared my successes, failures and frustrations over research and life. Your advice and assistance over these years has been extremely invaluable. I will also always recall our extremely fun early days when we took over from each other between lessons and having no idea what experiment we are conducting in the lab.

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Metallocyclic Ferrocenyl Ligands

Richards

2009

Chiral Ferrocenes in Asymmetric Catalysis

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This chapter is a comprehensive account of the synthesis and application of planar chiral ferrocene-based metallocycles. The first examples of the asymmetric synthesis of this class of compound date from the late 1970s, with the pioneering work of Viatcheslav Sokolov. However, it is only since the millennium that they have found widespread application, principally as catalysts for the allylic imidate rearrangement initially developed by Larry Overman.In the vast majority of cases the metal of the metallocyclic ring is palladium. Thus this class of compound is a sub-category of palladacycles [1] and/or metallacycles [2] in which the metal is bonded to an sp 2 , or less frequently, an sp 3 carbon atom. A significant feature of anionic bidentate ferrocenyl ligands is that the complexed metal M becomes a direct component of the element of planar chirality displayed by the resultant complex (Scheme 12.1). This contrasts to the majority of neutral bidentate ferrocene ligands [3] (e.g., P-P, P-N etc.), where the complexed metal is more remote from the basis of chirality [4]. Where M ¼ Pd(II) or Pt(II), the ancillary ligands L 1 and L 2 of the resultant square-planar complex are distinguished by the larger trans-influence/effect of the anionic carbon ligand compared to the neutral heteroatom (X) ligand component. This is revealed by the longer L 1 -M bond length compared to the corresponding L 2 -M bond length where L 1 ¼ L 2 1) , and also by analysis of the kinetic and thermodymanic products arising from ligand substitution [5]. The coordination axis perpendicular to the square plane, as represented by diastereotopic ligands L 3 and L 4 , is significantly influenced by the bulk of the metallocene. Thus associative ligand substitution reactions of square-planar complexes will most likely involve approach of the incoming ligand from the top face (L 3 ).

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Ferrocene studies III. Platinum and palladium complexes of [(dimethylamino)methyl]ferrocene

Cited by 15 publications

References 4 publications

From Pd(OAc)₂ to Chiral Catalysts: The Discovery and Development of Bifunctional Mono-N-Protected Amino Acid Ligands for Diverse C–H Functionalization Reactions

From Pd(OAc)₂ to Chiral Catalysts: The Discovery and Development of Bifunctional Mono-N-Protected Amino Acid Ligands for Diverse C–H Functionalization Reactions

The chemistry of cyclometalation : a comprehensive study on cycloiridated 1-arylalkylamine and imine complexes

Metallocyclic Ferrocenyl Ligands

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Ferrocene studies III. Platinum and palladium complexes of [(dimethylamino)methyl]ferrocene

Cited by 15 publications

References 4 publications

From Pd(OAc)2 to Chiral Catalysts: The Discovery and Development of Bifunctional Mono-N-Protected Amino Acid Ligands for Diverse C–H Functionalization Reactions

From Pd(OAc)2 to Chiral Catalysts: The Discovery and Development of Bifunctional Mono-N-Protected Amino Acid Ligands for Diverse C–H Functionalization Reactions

The chemistry of cyclometalation : a comprehensive study on cycloiridated 1-arylalkylamine and imine complexes

Metallocyclic Ferrocenyl Ligands

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From Pd(OAc)₂ to Chiral Catalysts: The Discovery and Development of Bifunctional Mono-N-Protected Amino Acid Ligands for Diverse C–H Functionalization Reactions

From Pd(OAc)₂ to Chiral Catalysts: The Discovery and Development of Bifunctional Mono-N-Protected Amino Acid Ligands for Diverse C–H Functionalization Reactions