153034-23-2Relevant academic research and scientific papers
Synthesis of Chromenoisoxazolidines from Substituted Salicylic Nitrones via Visible-Light Photocatalysis
Haun, Graham,Paneque, Alyson N.,Almond, David W.,Austin, Brooke E.,Moura-Letts, Gustavo
, p. 1388 - 1392 (2019)
This effort reports the first redox-neutral visible-light photocatalytic intramolecular dipolar cycloaddition for the diastereoselective synthesis of chromenoisoxazolidines. The authors have found that alkenylphenyl nitrones with a diverse substitution pattern on the aromatic ring and the alkenyl substituent undergo visible-light-promoted cycloadditions in the presence of catalytic amounts of Ru(bpy)3Cl2 in high yields and selectivities. Evidence indicates that the proposed redox-neutral pathway is the predominant photoredox mechanism for this transformation.
Cascade Claisen and Meinwald Rearrangement for One-Pot Divergent Synthesis of Benzofurans and 2 H-Chromenes
Song, Liyan,Su, Qian,Lin, Xi,Du, Zhihui,Xu, Huiyou,Ouyang, Ming-An,Yao, Hongliang,Tong, Rongbiao
supporting information, p. 3004 - 3009 (2020/04/20)
A new cascade approach has been developed for the one-pot four-step divergent synthesis of polysubstituted benzofurans and 2H-chromenes, featuring a novel cascade aromatic Claisen rearrangement/Meinwald rearrangement/dehydrative or oxidative cyclization. This new method was demonstrated with 39 examples tolerating different substitutions at an epoxide, allylic ether, and aromatic ring, and we showcased its utility with the first total synthesis of natural product liparacid A in seven steps.
Metal-free synthesis of phosphinoylchroman-4-ones via a radical phosphinoylation–cyclization cascade mediated by K2S2O8
Liu, Qiang,Lu, Weibang,Wang, Xiaoxia,Xie, Guanqun
supporting information, p. 1974 - 1982 (2020/10/02)
A variety of chroman-4-ones bearing phosphine oxide motifs were conveniently synthesized from readily available diphenylphosphine oxides and alkenyl aldehydes via a metal-free tandem phosphinoylation/cyclization protocol. The reaction utilizes K2S2O8 as oxidant and proceeds in DMSO/H2O at environmentally benign conditions with a broad substrate scope and afforded the title compounds in moderate yields.
Synthesis of chroman-4-one and indanone derivatives via silver catalyzed radical ring opening/coupling/cyclization cascade
Liu, Qiang,Xie, Guanqun,Wang, Qiang,Mo, Zhendong,Li, Chen,Ding, Shujiang,Wang, Xiaoxia
, (2019/09/10)
A variety of chroman-4-one and indanone derivatives were conveniently synthesized from readily available cyclopropanols and alkenyl aldehydes via a silver catalyzed radical ring-opening/coupling/cyclization cascade. The reaction proceeded under mild and neutral conditions with broad substrate scope and afforded the desired products in moderate to good yields. A probable mechanism for the cascade reaction was also proposed.
Cycloisomerization between Aryl Enol Ether and Silylalkynes under Ruthenium Hydride Catalysis: Synthesis of 2,3-Disubstituted Benzofurans
Ohno, Shohei,Takamoto, Kohei,Fujioka, Hiromichi,Arisawa, Mitsuhiro
supporting information, p. 2422 - 2425 (2017/05/12)
Metal-catalyzed cycloisomerization reactions of 1,n-enynes have become conceptually and chemically attractive processes in the search for atom economy, which is a key subject of current research. However, metal-catalyzed cycloisomerization between aryl enol ether and silylalkynes has not been developed. The ruthenium hydride complex catalyzed cycloisomerization between aryl enol ether and silylalkynes is reported to give benzofurans having useful functional groups, vinyl and trimethylsilylmethyl, on the 2- and 3-positions, respectively.
A cascade Claisen rearrangement/o-quinone methide formation/electrocyclization approach to 2H-chromenes
Song, Liyan,Huang, Fang,Guo, Liwen,Ouyang, Ming-An,Tong, Rongbiao
supporting information, p. 6021 - 6024 (2017/07/10)
A new approach has been developed for the synthesis of 8-substituted 2H-chromenes, featuring a novel cascade aromatic Claisen rearrangement/o-quinone methide formation/6π-electrocyclization. This new method was demonstrated with 28 examples tolerating different substitutions at alkenes, allylic and aromatic ring and with total syntheses of three 2H-chromene natural products.
The Synthesis of 5-Amino-dihydrobenzo[b]oxepines and 5-Amino-dihydrobenzo[b]azepines via Ichikawa Rearrangement and Ring-Closing Metathesis
Chwastek, Monika,Pieczykolan, Micha?,Stecko, Sebastian
, p. 9046 - 9074 (2016/10/17)
The combination of Ichikawa's rearrangement and a ring-closing metathesis reaction of allyl carbamates is presented as a method for the preparation of 5-amino-substituted 2,5-dihydro-benzo[b]oxepines, 2,5-dihydro-benzo[b]azepines, and 2,5-dihydro-benzo[b]thiepins. It was demonstrated that the use of nonracemic allyl carbamates enables the synthesis of enantioenriched benzo-fused seven-membered heterocycles. Finally, it was shown that further functionalization of the obtained structures allows access to pharmacologically active 5-amino-substituted 2,3,4,5-tetrahydro-1-benzo[b]oxepine scaffolds.
Organoselenium and DMAP co-catalysis: Regioselective synthesis of medium-sized halolactones and bromooxepanes from unactivated alkenes
Verma, Ajay,Jana, Sadhan,Prasad, Ch. Durga,Yadav, Abhimanyu,Kumar, Sangit
supporting information, p. 4179 - 4182 (2016/03/19)
A catalytic system consisting of bis(4-methoxyphenyl)selenide and 4-(dimethylamino)pyridine (DMAP) has been developed for the regioselective synthesis of medium-sized bromo/iodo lactones and bromooxepanes possessing high transannular strain. 77Se NMR, mass spectrometry and theoretical studies reveal that the reaction proceeds via a quaternary selenium intermediate.
Palladium-catalyzed intramolecular carboesterification of olefins
Li, Yang,Jardine, Katherine J.,Tan, Runyu,Song, Datong,Dong, Vy M.
, p. 9690 - 9692 (2010/04/28)
One catalyst three bonds: The title reaction between propiolic acids and unactivated olefins (see scheme; O red, Cl green) results in vicinal functionalization of the olefin, with the formation of new C-C and C-O bonds. Structurally complex 6,7,5-tricyclic ring systems are formed in a single step by this cascade chloropalladation and formal [3+2] cycloaddition.
Steric acceleration of intramolecular cycloaddition reactions
Orlek, Barry S.,Sammes, Peter G.,Weller, David J.
, p. 8179 - 8194 (2007/10/02)
Use of conformational constraints, induced by different ortho-substituents in 1-allyloxy-2-(substituted)methylbenzenes, where the substituent is a 1,3-dipole such as the azide or 3-oxidopyridinium group, can be employed to accelerate the 1,3-dipolar cycloaddition reaction. In this manner cycloadditions that otherwise do not proceed can be forced to react.
