Article
Chemistry, Physical
Jian-Hua Liu, Qing Zhou, Yao Lin, Zhu-Lian Wu, Tian Cai, Wei Wen, Yan-Min Huang, Qi-Xiang Guo
Summary: In this study, a highly efficient atom-economic asymmetric alpha-allylation method using chiral-aldehyde/palladium catalyst was reported. This method enables the asymmetric alpha-allylation of different 1,3-dienes and allenes with N-unprotected amino acid esters, leading to the synthesis of alpha,alpha-disubstituted chiral alpha-amino acid esters with high efficiency, good yields, and stereoselectivities. No N-allylation byproducts were observed in these reactions. Two reaction models were proposed based on mechanistic control experiments. Overall, this work demonstrates a new approach for preparing structurally diverse chiral amino acids and provides insights for developing chiral-aldehyde catalytic systems.
Article
Multidisciplinary Sciences
Thien Phuc Le, Shinji Tanaka, Masahiro Yoshimura, Kazuhiko Sato, Masato Kitamura
Summary: The authors report a mixed catalytic system consisting of Pd and Ru complexes for the asymmetric dehydrative condensation between cinnamyl-type allylic alcohols and beta-keto esters. The reaction proceeds under nearly neutral conditions, resulting in high regio-, diastereo-, and enantioselective α-mono-substituted products.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Zhao-Wei Wu, Wei Wen, Qi-Xiang Guo
Summary: A highly efficient biphenyl aldehyde-based ternary catalytic system is designed and used in the direct α-allylation reaction of N-unprotected amino acid esters and allyl alcohol acetates. The chemoselectivity of C-allylation and N-allylation is effectively controlled, and various racemic α,α-disubstituted amino acid esters are obtained in good-to-high yields. The target products can be easily converted into structurally diverse α,α-disubstituted amino acids at a gram scale.
Article
Chemistry, Physical
Chuan Wang, Rui Wang, Pei Fan
Summary: In this work, a highly enantioselective acyl C-H allylation of aldehydes and formamides was developed using a chiral PHOX nickel complex and tetrabutylammonium decatungstate (TBADT) as the cooperative catalysts. By employing readily available Morita-Baylis-Hillman adducts as the electrophilic allylating agent, the reaction allows for the synthesis of alpha-stereogenic beta,gamma-unsaturated 1,4-dicarbonyl compounds with high enantioselectivity. Preliminary mechanistic investigations suggest an enantioconvergent reaction pathway involving rapid kinetic resolution of starting allyl acetates through oxidative addition to Ni(0) followed by dynamic kinetic resolution of resultant allyl Ni(II) complexes via interaction with acyl radicals generated by TBADT-mediated homolytic acyl C-H bond cleavage.
Article
Chemistry, Physical
Chuan Wang, Rui Wang, Pei Fan
Summary: We developed a highly enantioselective acyl C-H allylation reaction, which can synthesize highly enantioselective α-stereogenic β,γ-unsaturated 1,4-dicarbonyl compounds.
Article
Chemistry, Multidisciplinary
Shinji Tanaka, Masato Kitamura
Summary: The modification of allyl alcohol to allyl ester or halide in dehydrative allylation reaction is achieved using two redox-mediated donor acceptor bifunctional catalyst systems, expanding the application scope and facilitating the utilization of various nucleophiles with aliphatic and aromatic allylic alcohols.
Article
Chemistry, Physical
Simon Sieger, Ilja Lubins, Bernhard Breit
Summary: A highly versatile palladium-catalyzed allylation reaction has been reported, providing a waste-free access to allylated nucleophiles with unlimited possibilities for further functionalization. The reaction can be conducted using propadiene in toluene, and the mechanism is supported by deuterium labeling experiments.
Article
Chemistry, Physical
Simon V. Sieger, Ilja Lubins, Bernhard Breit
Summary: A highly versatile palladium-catalyzed allylation reaction using various pronucleophiles has been reported. Through the use of propadiene in toluene, this reaction provides an efficient and waste-free method to obtain allylated nucleophiles with unlimited potential for further functionalization. The Pd/BINAP system is not only capable of adding N-, O-, and S-pronucleophiles, but also C-pronucleophiles to allene. The plausible mechanism is supported by deuterium labeling experiments.
Article
Chemistry, Multidisciplinary
Yoshikazu Horino, Toshinobu Korenaga
Summary: pi-Allylpalladium complexes can function as electrophilic or nucleophilic agents, with silylated and borylated pi-allylpalladium species showing unique reactivities that enable versatile transformations. The appropriate selection of ligands for these species allows control over reaction pathways.
Article
Chemistry, Physical
Ji Liu, Edward M. Laguna, Arun Raj Kizhakkayil Mangadan, Kyoungmin Kang, Aaron Aponick
Summary: A simple procedure for intermolecular enantioselective palladium-catalyzed decarboxylative allylation of beta-ketoacids is described. The method uses allyl carbonates as coupling substrates and allows direct access to alpha-allylated ketones with newly formed quaternary stereocenters. Experimental results suggest the transformation proceeds via an inner-sphere mechanism rather than the traditional outer-sphere process, and the reaction demonstrates potential usefulness in the enantioselective synthesis of (+)-adalinine.
Article
Chemistry, Multidisciplinary
Jun-Jie Tian, Rui-Rui Li, Gui-Xiu Tian, Xiao-Chen Wang
Summary: Here, we describe a new method for enantioselective C-H allylation of pyridines at C3 using a tandem borane and palladium catalysis. This method involves borane-catalyzed pyridine hydroboration, palladium-catalyzed enantioselective allylation of the resulting dihydropyridines with allylic esters, and air oxidation to afford the products. This method allows for the introduction of an allylic group at C3 with excellent regio- and enantioselectivities.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Kazuhiko Semba, Naoki Ohta, Fritz Paulus, Masaki Ohata, Yoshiaki Nakao
Summary: This new method allows for allylarylation of electron-deficient alkenes using aryl boronates and allylic carbonates as starting materials, leading to a variety of carbon skeletons. Mechanistic studies reveal that the reaction is facilitated by a cooperative catalysis involving Pd-0/Pd-II redox and Pd-II/Pd-II non-redox catalytic cycles.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Review
Chemistry, Organic
Vysakh Venugopalan Nair, Dhanarajan Arunprasath, Solai Pandidurai, Govindasamy Sekar
Summary: Dual catalysis enables unconventional transformations by synergistically activating two substrates without interference. Various combinations of transition metal catalysis with Lewis acid catalysis, photoredox catalysis, biocatalysis, or organocatalysis have been explored, with a particular focus on the integration of amine catalysts with transition metal catalysts.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Grant N. Shivers, Christopher Pigge
Summary: A method to introduce allyl or cinnamyl groups to 2- or 4-alkylpyridines is described. This method involves the use of catalytic [(eta(3)-allyl)PdCl](2) and PPh3 to transfer N-allyl groups to the pyridine periphery, with the formation of nucleophilic alkylidene dihydropyridine intermediates. Catalytic turnover and liberation of pyridine products is achieved by oxidative addition of Pd(0) to these activated allyl groups.
TETRAHEDRON LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Xiaobo Yang, Bowen Li, Huicong Xing, Ju Qiu, Teck-Peng Loh, Peizhong Xie
Summary: An environmentally friendly protocol for C-P bond construction was developed under metal- and solvent-free conditions. Various P-H species can be incorporated into the dehydrative cross-coupling process with allylic alcohols in the presence of B(C6F5)(3), yielding high yields of allylic organophosphorus compounds.
Article
Chemistry, Multidisciplinary
Masakiyo Mukai, Kazunori Nagao, Shigeru Yamaguchi, Hirohisa Ohmiya
Summary: A molecular field-based regression analysis was used to design chiral ligands with improved enantioselectivity in NHC-Cu-catalyzed asymmetric carbonyl additions.
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN
(2022)
Article
Chemistry, Organic
Koh Watanabe, Mitsutaka Takeda, Kazunori Nagao, Hirohisa Ohmiya
Summary: This article describes a catalytic reductive cross-coupling reaction between arylaldehydes and aryl electrophiles using a silylboronate as a terminal reductant. The protocol provides a new opportunity to access 1,1-diarylmethanol derivatives without the need for rare metals or highly basic organometallic reagents.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Masanari Nakagawa, Yuki Matsuki, Kazunori Nagao, Hirohisa Ohmiya
Summary: We have demonstrated the Markovnikov hydroalkoxylation of unactivated alkenes using alcohols through a triple catalysis involving photoredox, cobalt, and Brönsted acid catalysts. This triple catalysis allows the realization of three key elementary steps in a single catalytic cycle: Co(III) hydride generation, metal hydride hydrogen atom transfer (MHAT), and oxidation of the alkyl Co(III) complex. The precise control of protons and electrons by the three catalysts eliminates the need for strong acids and external reductants/oxidants in the conventional methods.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Multidisciplinary Sciences
Taiga Kodo, Kazunori Nagao, Hirohisa Ohmiya
Summary: This paper reports a new method of semipinacol rearrangement using photochemical approach, enabling the synthesis of compounds with sp(3)-rich scaffolds.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Yunosuke Takekawa, Taiga Kodo, Kazunori Nagao, Hiroyuki Kakei, Kohei Takeuchi, Yusuke Sasak, Hirohisa Ohmiya
Summary: This manuscript presents an organophotoredox-catalyzed decarboxylative fluorination of alkyl redox active esters with triethylamine trihydrofluoride. The reaction proceeds via a radical-polar crossover mechanism to produce a carbocation equivalent under non-acidic and transition metal free conditions. This protocol enables the synthesis of various tertiary alkyl and benzyl fluorides in an environmentally friendly manner.
Article
Chemistry, Organic
Tomotoki Matsuo, Kazunori Nagao, Hirohisa Ohmiya
Summary: In this study, a visible light-mediated organophotoredox catalysis was developed for the cross-coupling between aliphatic carboxylic acid-derived redox active esters and organosilanes. This protocol enables the formation of C(sp3)-C(sp3), C(sp3)-C(sp2), and C(sp3)-C(sp) bonds under transition-metal free and mild reaction conditions. Additionally, the radical relay-type dicarbofunctionalization of styrene derivatives using organosilanes and aliphatic redox active esters was demonstrated.
TETRAHEDRON LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Yunosuke Takekawa, Masanari Nakagawa, Kazunori Nagao, Hirohisa Ohmiya
Summary: In this study, a quadruple catalysis system involving N-heterocyclic carbene, cobalt, photoredox, and Bronsted base is demonstrated to achieve branch-selective hydroacylation of styrenes with aromatic and aliphatic aldehydes. This protocol provides a convenient and atom-economical method for the synthesis of branched ketones from readily available materials by transferring a formyl hydrogen of aldehydes as a hydrogen radical equivalent onto the terminal carbon of an alkene through controlled electron and proton transfers.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Rikako Nakamura, Takeru Yamazaki, Yui Kondo, Miho Tsukada, Yusuke Miyamoto, Nozomi Arakawa, Yuto Sumida, Taketoshi Kiya, Satoshi Arai, Hirohisa Ohmiya
Summary: Researchers have developed a new method for caging/uncaging bioactive molecules using a photo-cleavable carbon-boron bond. This method allows for the caging of previously uncageable molecules, such as acetylcholine, providing a unique tool for optopharmacology to study neuronal mechanisms.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Multidisciplinary Sciences
Kenji Ota, Kazunori Nagao, Dai Hata, Haruki Sugiyama, Yasutomo Segawa, Ryosuke Tokunoh, Tomohiro Seki, Naoya Miyamoto, Yusuke Sasaki, Hirohisa Ohmiya
Summary: This study demonstrates a light-driven radical-polar crossover mechanism for the tertiary alkylation of phosphorus atoms in nucleotides, enabling the synthesis of alkylphosphonate structures that are difficult to obtain using existing methods.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Ryoto Oya, Kenji Ota, Masaaki Fuki, Yasuhiro Kobori, Masahiro Higashi, Kazunori Nagao, Hirohisa Ohmiya
Summary: The biomimetic design based on the iron(iv)-oxo porphyrin & pi;-cation radical species in cytochrome P450 enzymes has been extensively studied. In this study, the functions of this species were translated to an & alpha;-ketoacyl phosphonium species comprised of non-metal atoms and used as a light-activated oxygenation auxiliary for ortho-selective oxygenation of anilines. The process exhibited high regioselectivity and chemoselectivity.
Article
Chemistry, Multidisciplinary
Ryoto Oya, Kenji Ota, Masaaki Fuki, Yasuhiro Kobori, Masahiro Higashi, Kazunori Nagao, Hirohisa Ohmiya
Summary: The biomimetic design of a transition metal complex based on the iron(iv)-oxo porphyrin & pi;-cation radical species has been translated to an & alpha;-ketoacyl phosphonium species for ortho-selective oxygenation of anilines. Visible light irradiation activates the excited state of the auxiliary, which acts as a transient oxidant, providing high regioselectivity and chemoselectivity.