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Rahman MM, Meng G, Bisz E, Dziuk B, Lalancette R, Szostak R, Szostak M. I tOct (I tOctyl) - pushing the limits of I tBu: highly hindered electron-rich N-aliphatic N-heterocyclic carbenes. Chem Sci 2023; 14:5141-5147. [PMID: 37206400 PMCID: PMC10189875 DOI: 10.1039/d3sc01006f] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/15/2023] [Indexed: 05/21/2023] Open
Abstract
ItBu (ItBu = 1,3-di-tert-butylimidazol-2-ylidene) represents the most important and most versatile N-alkyl N-heterocyclic carbene available in organic synthesis and catalysis. Herein, we report the synthesis, structural characterization and catalytic activity of ItOct (ItOctyl), C2-symmetric, higher homologues of ItBu. The new ligand class, including saturated imidazolin-2-ylidene analogues has been commercialized in collaboration with MilliporeSigma: ItOct, 929 298; SItOct, 929 492 to enable broad access of the academic and industrial researchers within the field of organic and inorganic synthesis. We demonstrate that replacement of the t-Bu side chain with t-Oct results in the highest steric volume of N-alkyl N-heterocyclic carbenes reported to date, while retaining the electronic properties inherent to N-aliphatic ligands, such as extremely strong σ-donation crucial to the reactivity of N-alkyl N-heterocyclic carbenes. An efficient large-scale synthesis of imidazolium ItOct and imidazolinium SItOct carbene precursors is presented. Coordination chemistry to Au(i), Cu(i), Ag(i) and Pd(ii) as well as beneficial effects on catalysis using Au(i), Cu(i), Ag(i) and Pd(ii) complexes are described. Considering the tremendous importance of ItBu in catalysis, synthesis and metal stabilization, we anticipate that the new class of ItOct ligands will find wide application in pushing the boundaries of new and existing approaches in organic and inorganic synthesis.
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Affiliation(s)
- Md Mahbubur Rahman
- Department of Chemistry, Rutgers University 73 Warren Street Newark NJ 07102 USA
| | - Guangrong Meng
- Department of Chemistry, Rutgers University 73 Warren Street Newark NJ 07102 USA
| | - Elwira Bisz
- Department of Chemistry, Opole University 48 Oleska Street Opole 45-052 Poland
| | - Błażej Dziuk
- Department of Chemistry, Wroclaw University of Science and Technology Norwida 4/6 14 Wroclaw 50-373 Poland
| | - Roger Lalancette
- Department of Chemistry, Rutgers University 73 Warren Street Newark NJ 07102 USA
| | - Roman Szostak
- Department of Chemistry, Wroclaw University F. Joliot-Curie 14 Wroclaw 50-383 Poland
| | - Michal Szostak
- Department of Chemistry, Rutgers University 73 Warren Street Newark NJ 07102 USA
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Tun SL, Mariappan SVS, Pigge FC. Imidazolidine Hydride Donors in Palladium-Catalyzed Alkyne Hydroarylation. J Org Chem 2022; 87:8059-8070. [PMID: 35649131 PMCID: PMC9490851 DOI: 10.1021/acs.joc.2c00725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Aldehyde-derived
imidazolidines participate as hydride donors in
intramolecular reductive Heck-type reactions. N,N′-Diphenylimidazolidines prepared from ortho-alkynyl benzaldehydes underwent regio- and stereoselective palladium-catalyzed
hydroarylation followed by formal 1,5-hydride transfer and reductive
elimination to afford substituted alkenes and imidazolium moieties,
the latter conveniently converted in situ to ring-opened benzanilides
to simplify product isolation. Internal alkynes were converted to
trisubstituted alkenes via a syn hydroarylation process,
while a terminal alkyne was converted to a cis alkene
via a formal trans hydroarylation reaction. Benzanilide
products could be converted to carboxylic acid derivatives under basic
conditions, resulting in the net conversion of alkynyl aldehydes to
alkenyl carboxylic acids. A styrene derivative with an attached N,N′-dimethylbenzimidazoline hydride
donor was also found to undergo an analogous hydroarylation/benzimidazoline
oxidation to give a diarylethane product.
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Affiliation(s)
- Soe L Tun
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - S V Santhana Mariappan
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States.,Central NMR Facility, University of Iowa, Iowa City, Iowa 52242, United States
| | - F Christopher Pigge
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
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Pi X, Qiao Y, Wang C, Li Z, Liu J, Wang L, Jin L, Ren A. Concentrations of organochlorine pesticides in placental tissue are not associated with risk for fetal orofacial clefts. Reprod Toxicol 2020; 98:99-106. [PMID: 32920085 DOI: 10.1016/j.reprotox.2020.08.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/04/2020] [Accepted: 08/27/2020] [Indexed: 11/28/2022]
Abstract
Previous epidemiological studies have shown that prenatal exposure to organochlorine pesticides (OCPs) entails a variety of adverse impacts on fetal health, but it is not yet known whether it is associated with risk for orofacial clefts (OFCs). This study of 103 fetuses or newborns with a diagnosis of OFCs (cases) and 103 healthy newborns without malformations (controls) examined whether prenatal exposure to OCPs, as indicated by their concentrations in placental tissue, is a risk factor for OFCs. No differences were found in the median concentrations of OCPs between cases and controls, with exception of o,p'-dichlorodiphenyldichloroethylene, o,p'-dichlorodiphenyldichloroethane, and total o,p'-dichlorodiphenyltrichloroethane (DDTs), whose concentrations were higher in controls than in cases (Ps < 0.05). Although higher concentrations of placental δhexachlorocyclohexane and isodrin were found to be associated with decreased risk for OFCs in logistic regression, no association was observed in the Bayesian kernel machine regression, a novel statistical model in analyzing exposure mixtures. Women who reported periconceptional folic acid supplementation had lower placental concentrations of DDTs than women who did not. In conclusion, no association between levels of OCPs in placental tissue and risk for OFCs was observed in this population. Supplementation with folic acid may help decrease the levels of DDTs in placental tissue, but further studies are needed to confirm this unexpected finding.
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Affiliation(s)
- Xin Pi
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Department of Social Medicine and Health Education, Peking University School of Public Health, Beijing 100191, China
| | - Yiran Qiao
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China
| | - Chengrong Wang
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China
| | - Zhiwen Li
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China
| | - Jufen Liu
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China
| | - Linlin Wang
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China
| | - Lei Jin
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China.
| | - Aiguo Ren
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
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4
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Yin S, Wei J, Wei Y, Jin L, Wang L, Zhang X, Jia X, Ren A. Organochlorine pesticides exposure may disturb homocysteine metabolism in pregnant women. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 708:135146. [PMID: 31787282 DOI: 10.1016/j.scitotenv.2019.135146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/18/2019] [Accepted: 10/22/2019] [Indexed: 06/10/2023]
Abstract
Maternal exposure to organochlorine pesticides (OCPs) has an adverse impact on maternal and fetal health, and excessive homocysteine is related to a variety of adverse pregnancy outcomes. Biomimetic studies suggest that OCPs interfere with folate-dependent pathways, but little evidence is available from studies with human subjects. This study explored whether exposure to OCPs interferes with the metabolism of homocysteine, which is folate dependent. A total of 313 pregnant women at 12-20 weeks gestation were recruited in Shanxi province, China, from 2014 to 2015. Plasma concentrations of 20 OCPs, including dichlorodiphenyltrichloroethane and metabolites (DDTs), hexachlorobenzene (HCB), and hexachlorocyclohexanes (HCHs), were analyzed by gas chromatography-mass spectrometry. Blood folate concentrations were analyzed by microbiological assay, and plasma homocysteine concentrations were determined by enzyme-linked immunosorbent assay. Information on demographics, lifestyle behaviors, and folic acid supplementation was collected by in-person interview. Of the women, 99% reported having taken folic acid supplements. Results of a logistic regression analysis showed that higher plasma levels of OCPs were associated with increased odds of higher plasma homocysteine after adjustment for potential confounding factors. Positive correlations were observed between plasma OCPs and plasma homocysteine concentrations: HCB (r = 0.176, p = 0.002), β-HCH (r = 0.172, p = 0.002), ρ,ρ'-DDE (r = 0.132, p = 0.020), ρ,ρ'-DDD (r = 0.161, p = 0.004), and ο,ρ'-DDT (r = 0.144, p = 0.011). Plasma concentrations of OCPs were negatively correlated with red blood cell (RBC) folate in the low-RBC-folate subgroup, but the correlations were not statistically significant. A positive correlation was observed between OCPs and homocysteine in the low-RBC-folate subgroup. These findings suggest that OCPs may disturb the folate-dependent homocysteine metabolism pathway.
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Affiliation(s)
- Shengju Yin
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Jing Wei
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Yihui Wei
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Lei Jin
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Linlin Wang
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Xuejuan Zhang
- Health Education Division, Shanxi Children's Hospital/Shanxi Maternal and Child Health Care Hospital, Taiyuan 030002, China
| | - Xiaoqian Jia
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Aiguo Ren
- Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Peking University, Beijing 100191, China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China.
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Denk MK, Milutinović NS, Dereviankin MY. Reduction of halocarbons to hydrocarbons by NADH models and NADH. CHEMOSPHERE 2019; 233:890-895. [PMID: 31340416 DOI: 10.1016/j.chemosphere.2019.05.169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 05/15/2019] [Accepted: 05/19/2019] [Indexed: 06/10/2023]
Abstract
The reduction of halocarbons by NADH models and NADH under ambient conditions is reported as a new type of reactivity pointing towards a hitherto unknown disruptive pathway for NADH/NADPH-dependent processes. The reaction was studied with the omnipresent pesticide DDT, the inhalation anesthetic halothane, and several simple halocarbons. The halide-hydride exchange represents a biochemical equivalent for the reduction of halocarbons by traditional synthetic reagents like silanes (R3Si-H) and stannanes (R3Sn-H). High precision thermochemical calculations (CBS-QB3) reveal the carbon-hydrogen bond dissociation energy of NADH (70.8 kcal·mol-1) to be lower than that of stannane (SnH4: 78.1 kcal·mol-1), approaching that of the elusive plumbane (PbH4: 68.9 kcal·mol-1). The ready synthetic accessibility of NADH models, their low carbon-hydrogen bond dissociation energy, and their dehalogenation activity in the presence of air and moisture recommend these compounds as substitutes for the air-sensitive or toxic metal hydrides currently employed in synthesis.
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Affiliation(s)
- Michael K Denk
- Department of Chemistry, University of Guelph, 50 Stone Road E., Guelph, Ontario, N1G 2W1, Canada.
| | - Nicholas S Milutinović
- Department of Chemistry, University of Guelph, 50 Stone Road E., Guelph, Ontario, N1G 2W1, Canada
| | - Mikhail Y Dereviankin
- Department of Chemistry, University of Guelph, 50 Stone Road E., Guelph, Ontario, N1G 2W1, Canada
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Poynder TB, Savaliya DP, Molino A, Wilson DJD, Dutton JL. Elimination of Ethene from 1,2-Diiodoethane Induced by N-Heterocyclic Carbene Halogen Bonding. Aust J Chem 2019. [DOI: 10.1071/ch19237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The attempted synthesis of N-heterocyclic carbene (NHC)-stabilised dicarbon (C2) fragments via nucleophilic substitution at 1,2-diiodoethane is reported. Rather than the expected SN2 pathway, clean elimination of ethene and formation of an iodoimidazolium cation was observed. The resistance towards nucleophilic substitution piqued interest, and subsequent investigation determined NHC-halogen bonding as the source. This is in contrast to reactions between NHCs and other alkyl halides, where substitution or elimination pathways are reported. A detailed theoretical study between these cases highlights the importance of iodine as a halogen bond donor compared with other halogens, and shows that NHCs are excellent halogen bond acceptors. This reactivity suggests potential for application of the halogen bonding interaction between NHCs and organic compounds.
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7
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Denk MK, Milutinović NS. Reductive dehalogenation of DDT with folate models: Formation of the DDT metabolite spectrum under biomimetic conditions. CHEMOSPHERE 2018; 191:408-411. [PMID: 29054081 DOI: 10.1016/j.chemosphere.2017.10.055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/04/2017] [Accepted: 10/09/2017] [Indexed: 06/07/2023]
Abstract
The insecticide DDT is an omnipresent environmental contaminant and an ongoing toxicological concern. The recent discovery that methylenetetrahydrofolate (MTHF) models are capable of reducing a range of halocarbons to hydrocarbons under biomimetic conditions has prompted us to investigate the possible role of MTHF in the metabolism of DDT. We now report that the reaction of MTHF models with DDT produces no less than five known in vivo metabolites of DDT, namely DDD, DDE, DDMU, DBP, and DDM. The capability of the MTHF models to produce the full spectrum of known DDT dehalogenation products is strong evidence that the mechanistically obscure metabolism of DDT may involve MTHF. The findings also suggest that DDT should be capable of disrupting folate-dependent pathways.
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Affiliation(s)
- Michael K Denk
- Department of Chemistry, University of Guelph, 50 Stone Road E., Guelph, Ontario, N1G 2W1, Canada.
| | - Nicholas S Milutinović
- Department of Chemistry, University of Guelph, 50 Stone Road E., Guelph, Ontario, N1G 2W1, Canada
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