264882-02-2Relevant articles and documents
B(C6F5)3-catalyzed O-H insertion reactions of diazoalkanes with phosphinic acids
Jiang, Jun,Zhang, Xinzhi,Zhang, Yangyang,Zhao, Jincheng
, p. 5772 - 5776 (2021/07/12)
A highly efficient base-, metal-, and oxidant-free catalytic O-H insertion reaction of diazoalkanes and phosphinic acids in the presence of B(C6F5)3has been developed. This powerful methodology provides a green approach towards the synthesis of a broad spectrum of α-phosphoryloxy carbonyl compounds with good to excellent yields (up to 99% yield). The protocol features the advantages of operational simplicity, high atom economy, practicality, easy scalability and environmental friendliness.
B(C6F5)3-Catalyzed site-selective N1-alkylation of benzotriazoles with diazoalkanes
Guo, Jing,Mandal, Dipendu,Stephan, Douglas W.,Wu, Yile,Zhao, Yunbo
, p. 7758 - 7761 (2021/08/13)
Alkylation of benzotriazoles is synthetically challenging, often leading to mixtures of N1 and N2 alkylation. Herein, metal-free catalytic site-selective N1-alkylation of benzotriazoles with diazoalkanes is described in the presence of 10 mol% of B(C6F5)3. These reactions provide N1-alkylated benzotriazoles in good to excellent yields and this protocol is successfully adapted to gram-scale syntheses as well as a derivative with antimicrobial activity.
α-Xanthylmethyl Ketones from α-Diazo ketones
López-Mendoza, Pedro,Miranda, Luis D.
, p. 3777 - 3790 (2021/07/07)
A simple and efficient method to obtain α-xanthylmethyl ketones from α-diazo ketones is described. The reaction proceeds through a protonation/nucleophilic substitution sequence in the presence of p -toluenesulfonic acid and potassium ethyl xanthogenate as the nucleophile. As α-diazo ketones can be readily synthesized from ubiquitous carboxylic acids, a broad variety of xanthates can be obtained, including examples from naturally occurring substrates.
Visible-light-promoted selective: O -alkylation of 2-pyridones with α-aryldiazoacetates
Yang, Jingya,Wang, Ganggang,Zhou, Hongyan,Li, Zhifeng,Ma, Ben,Song, Menghui,Sun, Rongxia,Huo, Congde
supporting information, p. 394 - 398 (2021/01/29)
A visible-light-promoted O-H insertion reaction between 2-pyridones and α-aryldiazoacetates has been developed. Upon visible light irradiation, the reaction proceeds smoothly under mild and catalyst-free conditions. A wide scope of 2-pyridones and α-aryldiazoacetates are well tolerated, and various O-alkylated 2-pyridones are obtained with perfect selectivity and good functional group tolerance. A photoinduced radical process is probably responsible for the excellent selectivity. This journal is
Diastereoselective Trapping of Transient Carboxylic Oxonium Ylides with α,β-Unsaturated 2-Acyl Imidazoles
Zhang, Mengchu,Zhang, Tianyuan,Zhang, Dan,Hu, Wenhao
supporting information, p. 4662 - 4667 (2020/09/23)
By developing a diastereoselective reaction of cyclopropene carboxylic acids with α,β-unsaturated 2-acyl imidazoles, we reported here a Michael-type trapping of transient carboxylic oxonium ylides. This transformation provides a direct approach for the construction of valuable γ-butenolide derivatives in good yields (60–99%) with high diastereoselectivities (up to >95:5 dr) under mild reaction conditions. (Figure presented.).
Catalytic Enantio- And Diastereoselective Cyclopropanation of 2-Azadienes for the Synthesis of Aminocyclopropanes Bearing Quaternary Carbon Stereogenic Centers
Shao, Xinxin,Malcolmson, Steven J.
supporting information, p. 7380 - 7385 (2019/10/02)
We report the catalytic enantio- and diastereoselective preparation of aminocyclopropanes by the cyclopropanation of terminal and (Z)-internal 2-azadienes with donor/acceptor carbenes derived from α-diazoesters. The resulting cyclopropanes bear quaternary carbon stereogenic centers vicinal to the amino-substituted carbon and are formed as a single diastereomer in up to 99:1 er and 97% yield with 0.5 mol % of Rh2(DOSP)4 and only 1.5 equiv of the diazo reagent. Transformations with internal azadienes afford cyclopropanes with three contiguous stereogenic centers.
Metal-Free Tandem Rearrangement/Lactonization: Access to 3,3-Disubstituted Benzofuran-2-(3H)-ones
Santi, Micol,Ould, Darren M. C.,Wenz, Jan,Soltani, Yashar,Melen, Rebecca L.,Wirth, Thomas
, p. 7861 - 7865 (2019/04/25)
A novel metal-free synthesis of 3,3-disubstituted benzofuran-2-(3H)-ones through reacting α-aryl-α-diazoacetates with triarylboranes is presented. Initially, triarylboranes were successfully investigated in α-arylations of α-diazoacetates, however in the presence of a heteroatom in the ortho position, the boron enolate intermediate undergoes an intramolecular rearrangement to form a quaternary center. The intermediate cyclizes to afford valuable 3,3-disubstituted benzofuranones in good yields.
Silica-supported HClO4 promotes catalytic solvent- and metal-free O-H insertion reactions with diazo compounds
Gallo, Rafael Douglas C.,Burtoloso, Antonio C. B.
, p. 4547 - 4556 (2018/10/17)
Solvent-free O-H insertion reactions in the presence of diazo carbonyl compounds were carried-out in very mild conditions. Unlike the traditional metal-catalysed version, employing rhodium acetate dimer, this method uses eco-friendly silica-supported HClO4 as the catalyst. Only 0.3 mol% of this Br?nsted acid catalyst, that can also be recycled several times, is necessary to guarantee very good yields (up to 97%) in the O-H insertion reactions. Reaction set-up is simple and permitted the preparation of forty-three α-hydroxy and α-alkoxy esters/ketones in just 1 h and at room temperature.
Three-Component Ring-Opening Reactions of Cyclic Ethers, α-Diazo Esters, and Weak Nucleophiles under Metal-Free Conditions
Lu, Lin,Chen, Chuwei,Jiang, Huanfeng,Yin, Biaolin
, p. 14385 - 14395 (2018/11/27)
A protocol for three-component reactions of cyclic ethers, α-diazo esters, and weak nitrogen, oxygen, carbon, and sulfur nucleophiles (pKa = 2.2-14.8) to afford a variety of structurally complex α-oxyalkylated esters is reported. These reactions involve intermolecular activation of the cyclic ether (present in excess) by the α-diazo ester to form an oxonium ylide under metal-free conditions, followed by ring opening by the nucleophile.
Catalyst-Free S–S Bond Insertion Reaction of a Donor/Acceptor-Free Carbene by a Radical Process: A Combined Experimental and Computational Study
Zheng, Yang,Bian, Rongjian,Zhang, Xiaolu,Yao, Ruwei,Qiu, Lihua,Bao, Xiaoguang,Xu, Xinfang
supporting information, p. 3872 - 3877 (2016/08/16)
Herein, a donor/acceptor-free carbene insertion reaction of an S–S bond through a radical process is presented. This catalyst-free reaction was thermally induced and provided the dithioketal products in moderate to high yields. A mechanism involving radical intermediates was proposed according to the computational study, and these intermediates were verified experimentally and intercepted for the first time by using a cross-coupling reaction.
