25574-11-2Relevant academic research and scientific papers
Structural Effects on Electrical Conduction of Conjugated Molecules Studied by Scanning Tunneling Microscopy
Ishida, Takao,Mizutani, Wataru,Choi, Nami,Akiba, Uichi,Fujihira, Masamichi,Tokumoto, Hiroshi
, p. 11680 - 11688 (2000)
We have studied electrical conduction of conjugated molecules with phenyl rings embedded into alkanethiol self-assembled monolayers (SAMs), to investigate the molecular structural effect on the electrical conduction. Scanning tunneling microscope (STM) images of this surface revealed that the conjugated molecules with phenyl rings adsorbed mainly on defects and domain boundaries of the pre-assembled alkanethiol (nonanethiol C9) SAM and formed conjugated domains. In the case of conjugated molecules with one or three methylene groups between the sulfur and phenyl rings, the measured height of the conjugated molecular domains depended on their lateral sizes, while a strong dependence was not observed in the case of conjugated molecules without a methylene group. By analyzing size dependence on the height of the conjugated molecular domain, we could evaluate the electronic conductivity of the molecular domains. As a result of the analysis, to increase the vertical conduction of the molecular domains, one methylene group was found to be necessary between the sulfur and aromatic phenyl rings. Local barrier heights on the conjugated molecular domains in all the cases were larger than on the C9 SAM surface, suggesting that the increase in the vertical conductivitity is not likely to be due to the lowering of the local barrier height, but can be attributed to the conjugated molecular adsorption. X-ray photoelectron spectra (XPS) and ultraviolet light photoelectron spectra (UPS) revealed that the carrier density among conjugated molecular SAMs does not depend on the number of methylene groups between the sulfur and phenyl rings, suggesting that the higher vertical conduction of conjugated molecules with one methylene group can probably be attributed to higher transfer probability of carriers during the STM measurements.
Synthesis of N-Alkyl Anilines from Arenes via Iron-Promoted Aromatic C-H Amination
Falk, Eric,Gasser, Valentina C. M.,Morandi, Bill
supporting information, p. 1422 - 1426 (2021/03/08)
We report both an intermolecular C-H amination of arenes to access N-methylanilines and an intramolecular variant for the synthesis of tetrahydroquinolines. A newly developed, highly electrophilic aminating reagent was key for the direct synthesis of unprotected N-methylanilines from simple arenes. The reactions display a broad functional group tolerance and employ catalytic amounts of a benign iron salt under mild reaction conditions.
Access to Trisubstituted Fluoroalkenes by Ruthenium-Catalyzed Cross-Metathesis
Nouaille, Augustin,Pannecoucke, Xavier,Poisson, Thomas,Couve-Bonnaire, Samuel
supporting information, p. 2140 - 2147 (2021/03/06)
Although the olefin metathesis reaction is a well-known and powerful strategy to get alkenes, this reaction remained highly challenging with fluororalkenes, especially the Cross-Metathesis (CM) process. Our thought was to find an easy accessible, convenient, reactive and post-functionalizable source of fluoroalkene, that we found as the methyl 2-fluoroacrylate. We reported herein the efficient ruthenium-catalyzed CM reaction of various terminal and internal alkenes with methyl 2-fluoroacrylate giving access, for the first time, to trisubstituted fluoroalkenes stereoselectively. Unprecedent TON for CM involving fluoroalkene, up to 175, have been obtained and the reaction proved to be tolerant and effective with a large range of olefin partners giving fair to high yields in metathesis products. (Figure presented.).
Chiral sulfoxide containing styrene monomer and preparation method thereof
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Paragraph 0043; 0049, (2021/06/22)
The present invention relates to a chiral sulfoxide containing a styrene monomer and a preparation method thereof. The chiral sulfoxide containing a styrene monomer comprises chiral sulfoxide, a styrene monomer and an extended chain located between the ch
Copper-Catalyzed Cross-Coupling between Alkyl (Pseudo)halides and Bicyclopentyl Grignard Reagents
Andersen, Claire,Bernardelli, Patrick,Cossy, Janine,Daumas, Marc,Ferey, Vincent,Guérinot, Amandine
supporting information, (2020/08/05)
The development of a copper-catalyzed cross-coupling between primary and secondary (pseudo)halides and bicyclopentyl Grignard reagents is reported. Highly strained bicyclopentanes can be cross-coupled with a large panel of primary alkyl mesylates and secondary alkyl iodides. The catalytic system is simple and cheap, and the reaction is general and chemoselective.
Nickel-Catalyzed Alkyl-Alkyl Cross-Electrophile Coupling Reaction of 1,3-Dimesylates for the Synthesis of Alkylcyclopropanes
Chen, Pan-Pan,Hong, Xin,Jarvo, Elizabeth R.,McGinnis, Tristan M.,Sanford, Amberly B.,Thane, Taylor A.
supporting information, (2020/03/23)
Cross-electrophile coupling reactions of two Csp3-X bonds remain challenging. Herein we report an intramolecular nickel-catalyzed cross-electrophile coupling reaction of 1,3-diol derivatives. Notably, this transformation is utilized to synthesize a range of mono- and 1,2-disubstituted alkylcyclopropanes, including those derived from terpenes, steroids, and aldol products. Additionally, enantioenriched cyclopropanes are synthesized from the products of proline-catalyzed and Evans aldol reactions. A procedure for direct transformation of 1,3-diols to cyclopropanes is also described. Calculations and experimental data are consistent with a nickel-catalyzed mechanism that begins with stereoablative oxidative addition at the secondary center.
Biocatalytic reduction of α,β-unsaturated carboxylic acids to allylic alcohols
Aleku, Godwin A.,Leys, David,Roberts, George W.
, p. 3927 - 3939 (2020/07/09)
We have developed robust in vivo and in vitro biocatalytic systems that enable reduction of α,β-unsaturated carboxylic acids to allylic alcohols and their saturated analogues. These compounds are prevalent scaffolds in many industrial chemicals and pharmaceuticals. A substrate profiling study of a carboxylic acid reductase (CAR) investigating unexplored substrate space, such as benzo-fused (hetero)aromatic carboxylic acids and α,β-unsaturated carboxylic acids, revealed broad substrate tolerance and provided information on the reactivity patterns of these substrates. E. coli cells expressing a heterologous CAR were employed as a multi-step hydrogenation catalyst to convert a variety of α,β-unsaturated carboxylic acids to the corresponding saturated primary alcohols, affording up to >99percent conversion. This was supported by the broad substrate scope of E. coli endogenous alcohol dehydrogenase (ADH), as well as the unexpected CC bond reducing activity of E. coli cells. In addition, a broad range of benzofused (hetero)aromatic carboxylic acids were converted to the corresponding primary alcohols by the recombinant E. coli cells. An alternative one-pot in vitro two-enzyme system, consisting of CAR and glucose dehydrogenase (GDH), demonstrates promiscuous carbonyl reductase activity of GDH towards a wide range of unsaturated aldehydes. Hence, coupling CAR with a GDH-driven NADP(H) recycling system provides access to a variety of (hetero)aromatic primary alcohols and allylic alcohols from the parent carboxylates, in up to >99percent conversion. To demonstrate the applicability of these systems in preparative synthesis, we performed 100 mg scale biotransformations for the preparation of indole-3-aldehyde and 3-(naphthalen-1-yl)propan-1-ol using the whole-cell system, and cinnamyl alcohol using the in vitro system, affording up to 85percent isolated yield.
Ir-catalyzed tandem hydroformylation-transfer hydrogenation of olefins with (trans-/cis-)formic acid as hydrogen source in presence of 1,10-phenanthroline
Chen, Xiao-Chao,Gao, Han,Liu, Lei,Liu, Ye,Lu, Yong,Xia, Fei,Yang, Shu-Qing
, p. 183 - 193 (2020/04/08)
The one-pot tandem hydroformylation-reduction to synthesize alcohols from olefins is in great demand but suffering from low yields, poor selectivity and harsh condition. Herein, 1,10-phenanthroline (L1) modified Ir-catalyst proved to exhibit multiple cata
Regulating Hydrogenation Chemoselectivity of α,β-Unsaturated Aldehydes by Combination of Transfer and Catalytic Hydrogenation
Zhou, Yangyang,Li, Zihao,Liu, Yanbo,Huo, Jia,Chen, Chen,Li, Qiling,Niu, Songyang,Wang, Shuangyin
, p. 1746 - 1750 (2020/02/25)
Two hydrogenation mechanisms, transfer and catalytic hydrogenation, were combined to achieve higher regulation of hydrogenation chemoselectivity of cinnamyl aldehydes. Transfer hydrogenation with ammonia borane exclusively reduced C=O bonds to get cinnamyl alcohol, and Pt-loaded metal–organic layers efficiently hydrogenated C=C bonds to synthesize phenyl propanol with almost 100 % conversion rate. The hydrogenation could be performed under mild conditions without external high-pressure hydrogen and was applicable to various α,β-unsaturated aldehydes.
Introduction of Cyclopropyl and Cyclobutyl Ring on Alkyl Iodides through Cobalt-Catalyzed Cross-Coupling
Andersen, Claire,Ferey, Vincent,Daumas, Marc,Bernardelli, Patrick,Guérinot, Amandine,Cossy, Janine
supporting information, p. 2285 - 2289 (2019/03/29)
A cobalt-catalyzed cross-coupling between alkyl iodides and cyclopropyl, cyclobutyl, and alkenyl Grignard reagents is disclosed. The reaction allows the introduction of strained rings on a large panel of primary and secondary alkyl iodides. The catalytic system is simple and nonexpensive, and the reaction is general, chemoselective, and diastereoconvergent. The alkene resulting from the cross-coupling can be transformed to substituted cyclopropanes using a Simmons-Smith reaction. The formation of radical intermediates during the coupling is hypothesized.
