- Direct, Site-Selective and Redox-Neutral α-C?H Bond Functionalization of Tetrahydrofurans via Quantum Dots Photocatalysis
-
As one of the most ubiquitous bulk reagents available, the intrinsic chemical inertness of tetrahydrofuran (THF) makes direct and site-selective C(sp3)?H bond activation difficult, especially under redox neutral condition. Here, we demonstrate that semiconductor quantum dots (QDs) can activate α-C?H bond of THF via forming QDs/THF conjugates. Under visible light irradiation, the resultant alkoxyalkyl radical directly engages in radical cross-coupling with α-amino radical from amino C?H bonds or radical addition with alkene or phenylacetylene, respectively. In contrast to stoichiometric oxidant or hydrogen atom transfer reagents required in previous studies, the scalable benchtop approach can execute α-C?H bond activation of THF only by a QD photocatalyst under redox-neutral condition, thus providing a broad of value added chemicals starting from bulk THFs reagent.
- Chen, Bin,Ci, Rui-Nan,Huang, Cheng,Liu, Zan,Qiao, Jia,Song, Zi-Qi,Tung, Chen-Ho,Wu, Li-Zhu
-
supporting information
p. 27201 - 27205
(2021/11/16)
-
- Ethyl cellulose derived porous iron@N-doped carbon material for N–H carbene insertion reaction
-
A newly developed, facile and sustainable strategy, in which zinc salt, melamine and ethyl cellulose are applied as pore-forming agent, nitrogen and carbon source respectively, has been disclosed for the synthesis of Fe/N-codoped carbon materials. This material exhibits excellent catalytic efficiency towards N–H carbene insertion reaction for the synthesis of unnatural amino acid derivatives. Fe/FeOx nanoparticles tranfer electrons to N-doped carbon owing to the Mott-Schottky Effect, which is beneficial to the formation of iron carbene intermediate. N-doping can offer more Lewis base sites, which promotes the proton transfer process. Fe/FeOx nanoparticles are coated with graphitic carbon, thereby avoiding the loss and deactivation of iron sites in this material. Therefore, this material can be reused at least four times without significant loss in activity.
- Lin, Yamei,Wang, Fei,Lu, Guo-Ping,Zhang, Xing
-
-
- Photoinduced iodine-mediated tandem dehydrogenative Povarov cyclisation/C-H oxygenation reactions
-
We report metal-free, photoinduced aerobic tandem dehydrogenative Povarov cyclisation/Csp3-H oxygenation reactions between N-aryl glycine esters and α-substituted styrenes, which efficiently lead to 4,4-disubstituted dihydroquinoline-3-ones under mild conditions. The reactions are mediated by iodine along with visible light irradiation, which allows for the in situ generation of the essential Br?nsted acid HI, to catalyse the key imine [4+2]-cycloaddition.
- Brasholz, Malte,Schendera, Eva,Villinger, Alexander
-
supporting information
p. 6912 - 6915
(2020/10/02)
-
- Functionalization of N-arylglycine esters: Electrocatalytic access to C-C bonds mediated by n-Bu4NI
-
An efficient electrocatalytic functionalization of N-arylglycine esters is reported. The protocol proceeds in an undivided cell under constant current conditions employing the simple, cheap and readily available n-Bu4NI as the mediator. In addition, it is demonstrated that the mediated process is superior to the direct electrochemical functionalization.
- Luo, Mi-Hai,Jiang, Yang-Ye,Xu, Kun,Liu, Yong-Guo,Sun, Bao-Guo,Zeng, Cheng-Chu
-
supporting information
p. 499 - 505
(2018/03/21)
-
- Engineering of RuMb: Toward a Green Catalyst for Carbene Insertion Reactions
-
The small, stable heme protein myoglobin (Mb) was modified through cofactor substitution and mutagenesis to develop a new catalyst for carbene transfer reactions. The native heme was removed from wild-type Mb and several Mb His64 mutants (H64D, H64A, H64V), and the resulting apoproteins were reconstituted with ruthenium mesoporphyrin IX (RuMpIX). The reconstituted proteins (RuMb) were characterized by UV-vis and circular dichroism spectroscopy and were used as catalysts for the N-H insertion of aniline derivatives and the cyclopropanation of styrene derivatives. The best catalysts for each reaction were able to achieve turnover numbers (TON) up to 520 for the N-H insertion of aniline, and 350 TON for the cyclopropanation of vinyl anisole. Our results show that RuMb is an effective catalyst for N-H insertion, with the potential to further increase the activity and stereoselectivity of the catalyst in future studies. Compared to native Mb ("FeMb"), RuMb is a more active catalyst for carbene transfer reactions, which leads to both heme and protein modification and degradation and, hence, to an overall much-reduced lifetime of the catalyst. This leads to lower TONs for RuMb compared to the iron-containing analogues. Strategies to overcome this limitation are discussed. Finally, comparison is also made to FeH64DMb and FeH64AMb, which have not been previously investigated for carbene transfer reactions.
- Wolf, Matthew W.,Vargas, David A.,Lehnert, Nicolai
-
p. 5623 - 5635
(2017/05/22)
-
- A series of robust metal-porphyrinic frameworks based on rare earth clusters and their application in N-H carbene insertion
-
We herein report a series of microporous metal-porphyrinic frameworks (MPFs), denoted as NUPF-2M, based on rare earth (RE) clusters. NUPF-2M represent the first examples of RE cluster-based MPFs, possessing a rarely seen shp-a topology and exhibiting high thermal and thermal stabilities. After a post-metallization process with FeCl3, NUPF-2M is catalytically active as an efficient heterogeneous catalyst for intermolecular N-H carbene insertion.
- Xu, Lei,Zhai, Meng-Ke,Wang, Fei,Sun, Lin,Du, Hong-Bin
-
p. 17108 - 17112
(2016/11/13)
-
- Enantioselective synthesis of arylglycine derivatives by direct C-H oxidative cross-coupling
-
A new method for the synthesis of chiral α-amino acid derivatives by enantioselective C-H arylation of N-aryl glycine esters with aryl boric acids in the presence of a chiral Pd(ii)-catalyst has been developed. This work successfully integrates the direct C-H oxidation with asymmetric arylation and exhibits excellent enantioselectivity. This journal is
- Wei, Xiao-Hong,Wang, Gang-Wei,Yang, Shang-Dong
-
supporting information
p. 832 - 835
(2015/02/05)
-
- Iron-catalyzed oxidative tandem reactions with TEMPO oxoammonium salts: Synthesis of dihydroquinazolines and quinolines
-
A straightforward iron-catalyzed divergent oxidative tandem synthesis of dihydroquinazolines and quinolines from N-alkylanilines using a TEMPO oxoammonium salt as a mild and nontoxic oxidant has been developed. Fe(OTf) 2 was the Lewis acid cata
- Rohlmann, Renate,Stopka, Tobias,Richter, Heinrich,Garcia Mancheno, Olga
-
p. 6050 - 6064
(2013/07/26)
-
- A water-soluble ruthenium glycosylated porphyrin catalyst for carbenoid transfer reactions in aqueous media with applications in bioconjugation reactions
-
Water-soluble [RuII(4-Glc-TPP)(CO)] (1, 4-Glc-TPP ) = meso-tetrakis(4-(β-D-glucosyl)phenyl)porphyrinato dianion) is an active catalyst for the following carbenoid transfer reactions in aqueous media with good selectivities and up to 100% conversions: intermolecular cyclopropanation of styrenes (up to 76% yield), intramolecular cyclopropanation of an allylic diazoacetate (68% yield), intramolecular ammonium/ sulfonium ylide formation/[2,3]-sigmatroptic rearrangement reactions (up to 91% yield), and intermolecular carbenoid insertion into N-H bonds of primary arylamines (up to 83% yield). This ruthenium glycosylated porphyrin complex can selectively catalyze alkylation of the N-terminus of peptides (8 examples) and mediate N-terminal modification of proteins (four examples) using a fluorescent-tethered diazo compound (15). A fluorescent group was conjugated to ubiquitin via 1-catalyzed alkene cyclopropanation with 15 in aqueous solution in two steps: (1) incorporation of an alkenic group by the reaction of N-hydroxysuccinimide ester 19 with ubiquitin and (2) cyclopropanation of the alkene-tethered Lys 6 ubiquitin (23) with the fluorescentlabeled diazoacetate 15 in the presence of a catalytic amount of 1. The corresponding cyclopropanation product (24) was obtained with -55% conversion based on MALDI-TOF mass spectrometry. The products 23, 24, and the N-terminal modified peptides and proteins were characterized by LC-MS/MS and/or SDS-PAGE analyses.
- Ho, Chi-Ming,Zhang, Jun-Long,Zhou, Cong-Ying,Chan, On-Yee,Yan, Jessie Jing,Zhang, Fu-Yi,Huang, Jie-Sheng,Che, Chi-Ming
-
supporting information; scheme or table
p. 1886 - 1894
(2010/04/25)
-