OrganometallicsPub Date : 2024-09-12DOI: 10.1021/acs.organomet.4c00281
Cameron H. M. Zheng, Carla A. Esslinger, Ole F. Dressler, Rebecca C. DiPucchio, Maria B. Ezhova, Laurel L. Schafer
{"title":"Tantalum Catalyzed Hydroaminoalkylation Enables a Telescoping Catalytic Reaction Sequence for the Synthesis of Benzoannulated Indolizidines and Quinolizidines","authors":"Cameron H. M. Zheng, Carla A. Esslinger, Ole F. Dressler, Rebecca C. DiPucchio, Maria B. Ezhova, Laurel L. Schafer","doi":"10.1021/acs.organomet.4c00281","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00281","url":null,"abstract":"The synthesis of benzoannulated indolizidines and quinolizidines is described through a telescoping reaction sequence featuring hydroaminoalkylation and nickel-catalyzed C–N bond coupling. An <i>in situ</i> generated tantalum (V) ureate catalyst is used to form new Csp<sup>3</sup>─Csp<sup>3</sup> bonds between saturated <i>N</i>-heterocycles and <i>ortho</i>-chlorostyrene enabled by the α C─H bond activation of the amine. The addition of a nickel C─N coupling catalyst generated from Ni(COD)<sub>2</sub> and DPPF to the reaction mixture allowed for cyclization. Our method leverages the regiodivergent branched and linear products accessed from <i>N</i>-heterocycle and styrene combinations, which are uniquely achieved by our tantalum catalyst to produce new <i>N</i>-heterocycle framework derivatives. Total isolated overall yields of up to 86% were achieved in a single pot. These advances highlight alternative bond disconnections that enable direct access to distinct new <i>N</i>-heterocycle derivatives through early transition metal catalyzed hydroaminoalkylation.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142180835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
OrganometallicsPub Date : 2024-09-12DOI: 10.1021/acs.organomet.4c00354
Kathryn J. Rynders, Daniel N. Huh, Zoe E. Stuart, Zoua Pa Vang, Ian A. Tonks
{"title":"Flash Communication: Ti-Catalyzed “Interrupted” Cascading Hydroamination of 1,6- and 1,7-En-ynes","authors":"Kathryn J. Rynders, Daniel N. Huh, Zoe E. Stuart, Zoua Pa Vang, Ian A. Tonks","doi":"10.1021/acs.organomet.4c00354","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00354","url":null,"abstract":"Herein, we report a new hydroaminative cyclization for 1,6- and 1,7-en-ynes using a simple Ti imido precatalyst, [py<sub>2</sub>TiCl<sub>2</sub>(NPh)]<sub>2</sub>. The well-known Ti imido + alkyne [2 + 2] azatitanacyclobutadiene cycloadduct intermediate can be further intercepted via insertion by tethered alkenes, followed by protonolysis of the resultant metallacycle to yield α-carbocyclic imine products through cascading C–N and C–C bond formation.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142180838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
OrganometallicsPub Date : 2024-09-12DOI: 10.1021/acs.organomet.4c0024710.1021/acs.organomet.4c00247
Hope A. Silva, Bevan S. Whitehead, Christopher D. Hastings, Chandan Kumar Tiwari, William W. Brennessel and Brandon R. Barnett*,
{"title":"Installation of Copper(I) and Silver(I) Sites into TREN-Based Porous Organic Cages via Postsynthetic Metalation","authors":"Hope A. Silva, Bevan S. Whitehead, Christopher D. Hastings, Chandan Kumar Tiwari, William W. Brennessel and Brandon R. Barnett*, ","doi":"10.1021/acs.organomet.4c0024710.1021/acs.organomet.4c00247","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00247https://doi.org/10.1021/acs.organomet.4c00247","url":null,"abstract":"<p >Porous organic cages (POCs) and metal–organic polyhedra (MOPs) function as zero-dimensional porous materials, able to mimic many functions of insoluble framework materials while offering processability advantages. A popular approach to access tailored metal-based motifs in extended network materials is postsynthetic metalation, which allows metal installation to be decoupled from framework assembly. Surprisingly, this approach has only sparingly been reported for molecular porous materials. In this report, we demonstrate postsynthetic metalation of tetrahedral [4 + 4] POCs assembled from tris(2-aminoethyl)amine (TREN) and 1,3,5-tris(4-formylphenyl)benzene. The trigonally symmetric TREN motif is a common chelator in coordination chemistry and, in the POCs explored herein, readily binds copper(I) and silver(I) to form cationic cages bearing discrete mononuclear coordination fragments. Metalation retains cage porosity, allowing us to compare the sorption properties of the parent organic and metalated cages. Interestingly, introduction of copper(I) facilitates activated oxygen chemisorption, demonstrating how targeted metalation can be exploited to tune the sorption characteristics of porous molecular materials.</p>","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acs.organomet.4c00247","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142555548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
OrganometallicsPub Date : 2024-09-12DOI: 10.1021/acs.organomet.4c0013810.1021/acs.organomet.4c00138
Claudia S. Zhang, Shreyas Rajesh, Abigail L. Moffett, Timothy H. Chen, Colin D. McMillen and Kerry-Ann Green*,
{"title":"Bis(benzimidazolin-2-ylidenes): Exploring the Impact of Ligand Properties in the Nickel-Catalyzed Suzuki–Miyaura Coupling","authors":"Claudia S. Zhang, Shreyas Rajesh, Abigail L. Moffett, Timothy H. Chen, Colin D. McMillen and Kerry-Ann Green*, ","doi":"10.1021/acs.organomet.4c0013810.1021/acs.organomet.4c00138","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00138https://doi.org/10.1021/acs.organomet.4c00138","url":null,"abstract":"<p >Bis(benzimidazolin-2-ylidenes) (bisNHCs) are explored as scaffolds for probing the impact of ligand properties in Ni-catalysis. Four well-defined, bench-stable propylene-bridged Ni(II) precatalysts of the type (bisNHC)NiBr<sub>2</sub> (<b>3a</b>–<b>3d</b>), with different wingtip groups have been synthesized and evaluated in the Ni-catalyzed Suzuki–Miyaura coupling (SMC). Three new complexes (<b>3b</b>–<b>3d</b>) were characterized by X-ray crystallography. The steric environments of the bisNHC ligands were quantified using the descriptors; buried volume (%<i>V</i><sub>Bur</sub>) and bite angle. The bisNHC electron-donating abilities were estimated computationally from the absolute minimum molecular electrostatic potential (MESP) at the carbene lone pair (<i>V</i><sub>min</sub>) and at the carbene nucleus (<i>V</i><sub>C</sub>). The bisNHC bearing cyclohexylmethyl wingtip groups exhibits the largest bite angle, highest %<i>V</i><sub>Bur</sub>, as well as the most negative <i>V</i><sub>min</sub> and <i>V</i><sub>C</sub> values. We established the catalytic competence of all precatalysts for the SMC of aryl sulfamates with arylboronic acids under mild conditions. Precatalyst (<b>3b</b>) bearing cyclohexylmethyl wingtip groups activates rapidly, completely and is consistently the most active. Precatalyst activation studies reveal the formation of Ni(I) species in situ. An independently synthesized model (bisNHC)Ni<sup>I</sup> precatalyst (<b>3e</b>) exhibits comparable catalytic activity to its Ni(II) counterpart (<b>3b</b>). Our findings provide insight into chelating NHCs as robust ligands for stabilizing Ni(I) and Ni(II) species.</p>","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acs.organomet.4c00138","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142276330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
OrganometallicsPub Date : 2024-09-12DOI: 10.1021/acs.organomet.4c0028110.1021/acs.organomet.4c00281
Cameron H. M. Zheng, Carla A. Esslinger, Ole F. Dressler, Rebecca C. DiPucchio, Maria B. Ezhova and Laurel L. Schafer*,
{"title":"Tantalum Catalyzed Hydroaminoalkylation Enables a Telescoping Catalytic Reaction Sequence for the Synthesis of Benzoannulated Indolizidines and Quinolizidines","authors":"Cameron H. M. Zheng, Carla A. Esslinger, Ole F. Dressler, Rebecca C. DiPucchio, Maria B. Ezhova and Laurel L. Schafer*, ","doi":"10.1021/acs.organomet.4c0028110.1021/acs.organomet.4c00281","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00281https://doi.org/10.1021/acs.organomet.4c00281","url":null,"abstract":"<p >The synthesis of benzoannulated indolizidines and quinolizidines is described through a telescoping reaction sequence featuring hydroaminoalkylation and nickel-catalyzed C–N bond coupling. An <i>in situ</i> generated tantalum (V) ureate catalyst is used to form new Csp<sup>3</sup>─Csp<sup>3</sup> bonds between saturated <i>N</i>-heterocycles and <i>ortho</i>-chlorostyrene enabled by the α C─H bond activation of the amine. The addition of a nickel C─N coupling catalyst generated from Ni(COD)<sub>2</sub> and DPPF to the reaction mixture allowed for cyclization. Our method leverages the regiodivergent branched and linear products accessed from <i>N</i>-heterocycle and styrene combinations, which are uniquely achieved by our tantalum catalyst to produce new <i>N</i>-heterocycle framework derivatives. Total isolated overall yields of up to 86% were achieved in a single pot. These advances highlight alternative bond disconnections that enable direct access to distinct new <i>N</i>-heterocycle derivatives through early transition metal catalyzed hydroaminoalkylation.</p>","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142517610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
OrganometallicsPub Date : 2024-09-12DOI: 10.1021/acs.organomet.4c00088
Gagik G. Melikyan, Nicole Babayans, Natalie Kalpakyan, Claire Herrera, Pavel Rublev, Nikolay V. Tkachenko, Alexander I. Boldyrev
{"title":"Cobalt-Complexed Acetylenic Tetrads, a Molecular Scaffold for Quadruple Ionic Functionalization Reactions","authors":"Gagik G. Melikyan, Nicole Babayans, Natalie Kalpakyan, Claire Herrera, Pavel Rublev, Nikolay V. Tkachenko, Alexander I. Boldyrev","doi":"10.1021/acs.organomet.4c00088","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00088","url":null,"abstract":"A methodology was developed for introducing nucleophiles into the α- and α′-positions of the dicobalt hexacarbonyl-complexed acetylenic tetrads. A synthetic algorithm included the entry of a given nucleophile to both termini of the acetylenic tetrad <b>A</b> (α-Nu<sup>1</sup>-α′-Nu<sup>1</sup>; α-Nu<sup>2</sup>-α′-Nu<sup>2</sup>), or a pair of select nucleophiles arranged unsymmetrically in opposing sequences (α-Nu<sup>1</sup>-α′-Nu<sup>2</sup>; α-Nu<sup>2</sup>-α′-Nu<sup>1</sup>). Thus, every substrate <b>A</b> and a pair of C-nucleophiles give rise to an organometallic rectangle (<b>B</b>-<b>E</b>) and synthetic octagon (<b>B</b>-<b>I</b>). The site-selective transformations that exploited the difference in thermodynamic stabilities of the α- and α′-cationoids, and thus in heterolytic bond dissociation energies (BDE) values, were coined the “quadruple ionic functionalization reactions.” The substrate and reagent bases were expanded to include aromatic carbo- and heterocycles as α-substituents, and aliphatic and aromatic reagents as nucleophiles. Density functional theory calculations allowed for identifying qualitative descriptors that explained the preponderant bond formation in more stabilized, albeit more hindered α-propargyl positions. In mechanistic terms, reactions at the competing sites (α- vs α-′) occupy distinctly different positions in the mechanistic continuum spanning the classical S<sub>N</sub>1 and S<sub>N</sub>2 processes. Overall, quadruple functionalization methodology allows for the practically limitless expansion of the acetylenic tetrads and a nucleophile base, and the completion of a multitude of organometallic rectangles and synthetic octagons.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142180834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
OrganometallicsPub Date : 2024-09-12DOI: 10.1021/acs.organomet.4c00327
Marc T. Bennett, Kwanwoo A. Park, T. Brent Gunnoe
{"title":"Rhodium-Catalyzed Arene Alkenylation: Selectivity and Reaction Mechanism as a Function of In Situ Oxidant Identity","authors":"Marc T. Bennett, Kwanwoo A. Park, T. Brent Gunnoe","doi":"10.1021/acs.organomet.4c00327","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00327","url":null,"abstract":"Rhodium catalyzed arene alkenylation reactions with arenes and olefins using dioxygen as the direct oxidant (e.g., <i>ACS Catal.</i> <b>2020</b>, <i>10</i>, 11519), Cu(II) carboxylates (e.g., <i>Science</i> <b>2015</b>, <i>348</i>, 421; <i>J. Am. Chem. Soc.</i> <b>2017</b>, <i>139</i>, 5474) or Fe(III) carboxylate clusters (e.g., <i>ACS Catal.</i> <b>2024,</b> <i>14</i>, 10295), in the presence or absence of dioxygen, have been reported. These processes involve heating catalyst precursor [(η<sup>2</sup>-C<sub>2</sub>H<sub>4</sub>)<sub>2</sub>Rh(μ-OAc)]<sub>2</sub>, olefin, arene, and oxidant at temperatures between 120 and 200 °C. Herein, we report comparative studies of Rh-catalyzed arene alkenylation as a function of oxidant identity. This work includes comparisons of catalysis using Cu(II) carboxylates in the presence and absence of dioxygen, catalysis with only dioxygen as the oxidant, and Fe(III) carboxylates in the presence and absence of dioxygen. We report studies of catalysis with each oxidant including reagent concentration dependencies and kinetic isotope effect experiments using C<sub>6</sub>H<sub>6</sub> or C<sub>6</sub>D<sub>6</sub> and protio- or deutero carboxylic acid. Additionally, we probe ortho/meta/para regioselectivity for reactions of ethylene with monosubstituted arenes and Markovnikov/anti-Markovnikov selectivity with monosubstituted olefins. These studies indicate that the variation of oxidant identity impacts catalyst speciation, the reaction mechanism, and the reaction rate. Consequently, distinct Markovnikov/anti-Markovnikov and ortho/meta/para selectivities are observed for catalysis with each oxidant.","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142180839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
OrganometallicsPub Date : 2024-09-12DOI: 10.1021/acs.organomet.4c0008810.1021/acs.organomet.4c00088
Gagik G. Melikyan*, Nicole Babayans, Natalie Kalpakyan, Claire Herrera, Pavel Rublev, Nikolay V. Tkachenko and Alexander I. Boldyrev*,
{"title":"Cobalt-Complexed Acetylenic Tetrads, a Molecular Scaffold for Quadruple Ionic Functionalization Reactions","authors":"Gagik G. Melikyan*, Nicole Babayans, Natalie Kalpakyan, Claire Herrera, Pavel Rublev, Nikolay V. Tkachenko and Alexander I. Boldyrev*, ","doi":"10.1021/acs.organomet.4c0008810.1021/acs.organomet.4c00088","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00088https://doi.org/10.1021/acs.organomet.4c00088","url":null,"abstract":"<p >A methodology was developed for introducing nucleophiles into the α- and α′-positions of the dicobalt hexacarbonyl-complexed acetylenic tetrads. A synthetic algorithm included the entry of a given nucleophile to both termini of the acetylenic tetrad <b>A</b> (α-Nu<sup>1</sup>-α′-Nu<sup>1</sup>; α-Nu<sup>2</sup>-α′-Nu<sup>2</sup>), or a pair of select nucleophiles arranged unsymmetrically in opposing sequences (α-Nu<sup>1</sup>-α′-Nu<sup>2</sup>; α-Nu<sup>2</sup>-α′-Nu<sup>1</sup>). Thus, every substrate <b>A</b> and a pair of C-nucleophiles give rise to an organometallic rectangle (<b>B</b>-<b>E</b>) and synthetic octagon (<b>B</b>-<b>I</b>). The site-selective transformations that exploited the difference in thermodynamic stabilities of the α- and α′-cationoids, and thus in heterolytic bond dissociation energies (BDE) values, were coined the “quadruple ionic functionalization reactions.” The substrate and reagent bases were expanded to include aromatic carbo- and heterocycles as α-substituents, and aliphatic and aromatic reagents as nucleophiles. Density functional theory calculations allowed for identifying qualitative descriptors that explained the preponderant bond formation in more stabilized, albeit more hindered α-propargyl positions. In mechanistic terms, reactions at the competing sites (α- vs α-′) occupy distinctly different positions in the mechanistic continuum spanning the classical S<sub>N</sub>1 and S<sub>N</sub>2 processes. Overall, quadruple functionalization methodology allows for the practically limitless expansion of the acetylenic tetrads and a nucleophile base, and the completion of a multitude of organometallic rectangles and synthetic octagons.</p>","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142276372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
OrganometallicsPub Date : 2024-09-12DOI: 10.1021/acs.organomet.4c0035410.1021/acs.organomet.4c00354
Kathryn J. Rynders, Daniel N. Huh, Zoe E. Stuart, Zoua Pa Vang and Ian A. Tonks*,
{"title":"Flash Communication: Ti-Catalyzed “Interrupted” Cascading Hydroamination of 1,6- and 1,7-En-ynes","authors":"Kathryn J. Rynders, Daniel N. Huh, Zoe E. Stuart, Zoua Pa Vang and Ian A. Tonks*, ","doi":"10.1021/acs.organomet.4c0035410.1021/acs.organomet.4c00354","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00354https://doi.org/10.1021/acs.organomet.4c00354","url":null,"abstract":"<p >Herein, we report a new hydroaminative cyclization for 1,6- and 1,7-en-ynes using a simple Ti imido precatalyst, [py<sub>2</sub>TiCl<sub>2</sub>(NPh)]<sub>2</sub>. The well-known Ti imido + alkyne [2 + 2] azatitanacyclobutadiene cycloadduct intermediate can be further intercepted via insertion by tethered alkenes, followed by protonolysis of the resultant metallacycle to yield α-carbocyclic imine products through cascading C–N and C–C bond formation.</p>","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142276376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
OrganometallicsPub Date : 2024-09-11DOI: 10.1021/acs.organomet.4c0026610.1021/acs.organomet.4c00266
Feiyun Jia*, Chenghua Zhang, Yongsheng Yang and Bo Zhang*,
{"title":"Mechanistic Insights into Rh-Catalyzed Asymmetric Synthesis of Silicon-Stereogenic Silazanes: The Origin of Enantioselectivity","authors":"Feiyun Jia*, Chenghua Zhang, Yongsheng Yang and Bo Zhang*, ","doi":"10.1021/acs.organomet.4c0026610.1021/acs.organomet.4c00266","DOIUrl":"https://doi.org/10.1021/acs.organomet.4c00266https://doi.org/10.1021/acs.organomet.4c00266","url":null,"abstract":"<p >The catalytic asymmetric synthesis of silazanes is always a challenging task. Here, a highly enantioselective synthesis of silicon-stereogenic silazanes was investigated to elucidate the protocol’s principal features and to clarify the origin of the enantioselectivity by using DFT calculations. The computational results indicate that the total free energy barrier for the conversion is 19.9 kcal/mol, which is reasonable given the current reaction conditions. Consistent with the experimental findings, the calculations indicate that σ-bond metathesis (N–H bond cleavage) is the rate-determining step for this transformation. Both pathways 1 and 2 toward <i>S</i>- or <i>R</i>-configuration products were investigated computationally. We found that the main enantiomer product of this transformation is determined by the kinetically more favorable main reaction pathway 1. Calculations indicate that the loss of one or the other H on the dihydrosilane will lock the product chirality; therefore, the oxidative addition is the enantioselectivity-determining step. Non-covalent interaction (NCI) analysis confirms that a difference in steric hindrance is responsible for the enantioselectivity of the protocol. Additionally, calculations confirm that the electron-donating group on aniline appropriately lowers the free energy barrier relative to the electron-withdrawing group (Δ<i>G</i> = 15.5 vs 21.6 kcal/mol), thereby accelerating the conversion.</p>","PeriodicalId":56,"journal":{"name":"Organometallics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142276368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}