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Watanabe N, Imoto H, Naka K. Synthesis of a series of octaalkoxy-substituted cage silsesquioxanes catalyzed by zinc acetate. Dalton Trans 2024. [PMID: 38817162 DOI: 10.1039/d4dt01008f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
Octaalkoxy-substituted polyhedral oligomeric silsesquioxane (8RO-POSS) is an attractive starting material for producing silicone resins. However, polymers derived from 8RO-POSS via the sol-gel process have seldom been reported owing to their synthetic difficulty. In this study, we attempted to use zinc acetate (Zn(OAc)2) as the catalyst for the synthesis of a series of 8RO-POSS from octahydrido-POSS (8H-POSS). The reaction conditions were optimized using heptaisobutyl monohydride-POSS (7iBu1H-POSS) as a model reaction. The desired product was obtained in 96% yield under optimized conditions. The alkoxylation of 8H-POSS was performed using methanol (MeOH), ethanol (EtOH), isopropyl alcohol (i-PrOH), and tert-butyl alcohol (t-BuOH) in the presence of Zn(OAc)2 as the catalyst. Although octamethoxy-POSS (8MeO-POSS) was isolated in the presence of a byproduct, octaethoxy-POSS (8EtO-POSS) and octaisopropoxy-POSS (8iPrO-POSS) were obtained in high yields. The degree of alkoxylation was 55% in the case of using t-BuOH. The structures of 8MeO-POSS, 8EtO-POSS, and 8iPrO-POSS were confirmed by FT-IR, 1H-, and 29Si-NMR and MALDI-TOF-MS analyses. Compared to the random silicate obtained by base-treated tetramethoxysilane (TMOS), base-treated 8EtO-POSS and 8iPrO-POSS showed that the cage structures were maintained even after the formation of condensed silicate structures via a condensation reaction.
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Affiliation(s)
- Naoki Watanabe
- Faculty of Molecular Chemistry and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
- Materials Innovation Lab, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
- JNC Petrochemical Corporation, 5-1, Goikaigan, Ichihara, Chiba 290-8551, Japan
| | - Hiroaki Imoto
- Faculty of Molecular Chemistry and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
- Materials Innovation Lab, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Kensuke Naka
- Faculty of Molecular Chemistry and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
- Materials Innovation Lab, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
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Mandal C, Joshi S, Das S, Mishra S, Mukherjee D. 2-Anilidomethylpyridine-Derived Three-Coordinate Zinc Hydride: The Journey Unveils Anilide Backbone's Reactive Nature. Inorg Chem 2024; 63:739-751. [PMID: 38127496 DOI: 10.1021/acs.inorgchem.3c03673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Low-coordinate heteroleptic zinc hydrides are catalytically important but rare and synthetically challenging. We herein report three-coordinate monomeric zinc hydride on a 2-anilidomethylpyridine framework (NNL). The synthetic success comes through systematically screening a few different routes from different precursors. During the process, the ligand's anilide backbone interestingly appears to be more reactive than Zn's terminal site to electrophilic Lewis and Brønsted acids. The proligand NNLH reacts with [Zn{N(SiMe3)2}2] and ZnEt2 to give [(NNL)ZnA] (A = N(SiMe3)2 (1), Et(2)). Both are inert to PhSiH3 and H2 but react with HBpin only through the internal Zn-Nanilide bond to give the borylated ligand NNLBpin (3). The reactions of 1 and 2 with Ph3EOH (E = C, Si) afford a series of divergent compounds like [(NNLH)Zn(OSiPh3)2] (4), [Zn3(OSiPh3)4Et2] (5), and [EtZn(OCPh3)] (6). But in all cases, it is invariably the Zn-Nanilide bond protonated by the -OH with equal or higher preference than the terminal Zn-N or Zn-C bonds. A DFT analysis rationalizes the origin of such a reactivity pattern. Realizing that an acid-free route might be the key, reacting [(NNL)Li] with ZnBr2 gives [(NNL)Zn(μ-Br)]2 (7), which on successively treating with KOSiPh3 and PhSiH3 gives the desired [(NNL)ZnH] (8) as a three-coordinate monomer with a terminal Zn-H bond. Estimating the ligand steric in 8 shows the openness in Zn's coordination sphere, a desired criterion for efficient catalysis. This and a positive influence of the pyridyl sidearm is reflected in 8's superior activity in hydroborating PhC(O)Me by HBpin in comparison to Jones' two-coordinate anilido zinc hydride.
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Affiliation(s)
- Chhotan Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Shalini Joshi
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India
| | - Sanjay Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Sabyashachi Mishra
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India
| | - Debabrata Mukherjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
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Sen A, Kumar R, Tewari T, Gonnade RG, Chikkali SH. Iron-Catalyzed Alkoxylation, Dehydrogenative-Polymerization and Tandem Hydrosilylative-Alkoxylation. Chemistry 2023; 29:e202301375. [PMID: 37285327 DOI: 10.1002/chem.202301375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/09/2023]
Abstract
Alkoxylation, hydrosilylative-alkoxylation, and dehydrogenative-polymerization are some of the most widely used transformations in synthetic chemistry. However, these transformations are traditionally catalyzed by precious, and rare late-transition metals. Presented here is a molecularly defined iron complex that catalyzes alkoxylation, tandem hydrosilylative-alkoxylation, and dehydrogenative polymerization of silanes under mild conditions. The iron complex [Fe(CO)4 (H)(SiPh3 )] 1 catalyzes a direct Si-O coupling reaction between an array of silanes and alcohols to produce desired alkoxysilanes in excellent yield, with H2 as the only byproduct. The iron catalyst tolerates various functional groups and provides access to 20 alkoxysilanes, including essential molecules such as β-citronellol and cholesterol. Further, complex 1 catalyzes the polymerization of renewable diol and silane monomer to produce a renewable and degradable poly(isosorbide-silyl ether). Remarkably, complex 1 catalyzes a tandem hydrosilylative-alkoxylation of alkynes under mild conditions to yield unsaturated silyl ethers. The synthetic utility has been demonstrated by gram-scale alkoxylation and hydrosilylative-alkoxylation reactions.
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Affiliation(s)
- Anirban Sen
- Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, MH, India
- Academy of Scientific and Innovative Research (AcSIR) Sector 19, Kamla Nehru Nagar, Ghaziabad, 201002, U. P., India
| | - Rohit Kumar
- Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, MH, India
- Academy of Scientific and Innovative Research (AcSIR) Sector 19, Kamla Nehru Nagar, Ghaziabad, 201002, U. P., India
| | - Tanuja Tewari
- Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, MH, India
- Academy of Scientific and Innovative Research (AcSIR) Sector 19, Kamla Nehru Nagar, Ghaziabad, 201002, U. P., India
| | - Rajesh G Gonnade
- Academy of Scientific and Innovative Research (AcSIR) Sector 19, Kamla Nehru Nagar, Ghaziabad, 201002, U. P., India
- Center for Materials Characterization, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, MH, India
| | - Samir H Chikkali
- Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, MH, India
- Academy of Scientific and Innovative Research (AcSIR) Sector 19, Kamla Nehru Nagar, Ghaziabad, 201002, U. P., India
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Harinath A, Karmakar H, Kisan DA, Nayek HP, Panda TK. NHC-Zn alkyl catalyzed cross-dehydrocoupling of amines and silanes. Org Biomol Chem 2023; 21:4237-4244. [PMID: 37139558 DOI: 10.1039/d3ob00453h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
An N-heterocyclic carbene-zinc alkyl complex [ImDippZn(CH2CH3)2] (Im = imidazol-2-ylidene and Dipp = 2,6-diisopropylphenyl) acts as a catalyst in the cross-dehydrogenative coupling (CDC) of a wide range of primary and secondary amines and hydrosilanes to yield a substantial quantity of the corresponding aminosilanes with good chemoselectivity at room temperature. A broad substrate scope was observed during the zinc-catalyzed CDC reaction. Two zinc complexes, [{ImMesZn(μ-NHPh)(NHPh)}2] (Mes = mesityl) (3) and [{ImDippZn(CH2CH3)(μ-H)}2] (4), were isolated and structurally characterized as intermediates through controlled reactions to ascertain the CDC mechanism.
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Affiliation(s)
- Adimulam Harinath
- Department of Chemistry and Chemical Biology, Indian Institute of Technology Hyderabad, Kandi - 502 284, Sangareddy, Telangana, India.
| | - Himadri Karmakar
- Department of Chemistry and Chemical Biology, Indian Institute of Technology Hyderabad, Kandi - 502 284, Sangareddy, Telangana, India.
| | - Devadkar Ajitaro Kisan
- Department of Chemistry and Chemical Biology, Indian Institute of Technology Hyderabad, Kandi - 502 284, Sangareddy, Telangana, India.
| | - Hari Pada Nayek
- Department of Applied Chemistry. Indian Institute of Technology (ISM) Dhanbad, Dhanbad 826004, Jharkhand, India
| | - Tarun K Panda
- Department of Chemistry and Chemical Biology, Indian Institute of Technology Hyderabad, Kandi - 502 284, Sangareddy, Telangana, India.
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Kuciński K, Stachowiak-Dłużyńska H, Hreczycho G. Catalytic silylation of O–nucleophiles via Si–H or Si–C bond cleavage: A route to silyl ethers, silanols and siloxanes. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214456] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Patnaik S, Kanbur U, Ellern A, Sadow AD. Hydrosilane σ-Adduct Intermediates in an Adaptive Zinc-Catalyzed Cross-dehydrocoupling of Si-H and O-H Bonds. Chemistry 2021; 27:10428-10436. [PMID: 33876468 PMCID: PMC8362191 DOI: 10.1002/chem.202101146] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Indexed: 11/09/2022]
Abstract
Three-coordinate Ph BOXMe 2 ZnR (Ph BOXMe 2 =phenyl-(4,4-dimethyl-oxazolinato; R=Me: 2 a, Et: 2 b) catalyzes the dehydrocoupling of primary or secondary silanes and alcohols to give silyl ethers and hydrogen, with high turnover numbers (TON; up to 107 ) under solvent-free conditions. Primary and secondary silanes react with small, medium, and large alcohols to give various degrees of substitution, from mono- to tri-alkoxylation, whereas tri-substituted silanes do not react with MeOH under these conditions. The effect of coordinative unsaturation on the behavior of the Zn catalyst is revealed through a dramatic variation of both rate law and experimental rate constants, which depend on the concentrations of both the alcohol and hydrosilane reactants. That is, the catalyst adapts its mechanism to access the most facile and efficient conversion. In particular, either alcohol or hydrosilane binds to the open coordination site on the Ph BOXMe 2 ZnOR catalyst to form a Ph BOXMe 2 ZnOR(HOR) complex under one set of conditions or an unprecedented σ-adduct Ph BOXMe 2 ZnOR(H-SiR'3 ) under other conditions. Saturation kinetics provide evidence for the latter species, in support of the hypothesis that σ-bond metathesis reactions involving four-centered electrocyclic 2σ-2σ transition states are preceded by σ-adducts.
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Affiliation(s)
- Smita Patnaik
- Department of ChemistryIowa State UniversityAmesIA 50011USA
- US Department of Energy Ames LaboratoryIowa State UniversityAmesIA 50011USA
| | - Uddhav Kanbur
- Department of ChemistryIowa State UniversityAmesIA 50011USA
- US Department of Energy Ames LaboratoryIowa State UniversityAmesIA 50011USA
| | - Arkady Ellern
- Department of ChemistryIowa State UniversityAmesIA 50011USA
| | - Aaron D. Sadow
- Department of ChemistryIowa State UniversityAmesIA 50011USA
- US Department of Energy Ames LaboratoryIowa State UniversityAmesIA 50011USA
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