153034-24-3Relevant academic research and scientific papers
Catalyst-free synthesis of diversely substituted 6H-benzo[c]chromenes and 6H-benzo[c]chromen-6-ones in aqueous media under MWI
He, Yan,Zhang, Xinying,Cui, Liangyan,Wang, Jianji,Fan, Xuesen
, p. 3429 - 3435 (2012)
In this paper, a catalyst-free synthesis of diversely substituted 6H-benzo[c]chromenes and 6H-benzo[c]chromen-8-ols via cascade reactions of 2-(2-(allyloxy)phenyl)furan and 2-(2-(prop-2-ynyloxy)phenyl)furan, featured with intramolecular Diels-Alder reactions of furan with unactivated alkene/alkyne in aqueous media under MWI, was developed. In addition, an environmentally friendly oxidation of 6H-benzo[c]chromenes into the corresponding benzo[c]chromen-6-ones using aqueous H2O2 as an oxidant, in the absence of any activator/catalyst, was also revealed.
tert-Butyl Hydroperoxide-Initiated Radical Cyclization of 1-(Allyloxy)-2-(1-Arylvinyl)Benzenes with Sulfinic Acids to Access Sulfonated Benzoxepines
Kuang, Kaimo,Wu, Meixia,Wu, Sixin,Xia, Ziqin,Xu, Qiankun,Zhang, Man,Zhou, Nengneng
supporting information, p. 3491 - 3495 (2021/06/28)
A tert-butyl hydroperoxide-initiated radical cyclization of 1-(allyloxy)-2-(1-arylvinyl)benzenes with sulfinic acids for the construction of sulfonated benzoxepines is developed. This reaction involves a radical pathway and offers a straightforward route to the formation of seven-membered ring via sulfonylation/cyclization process. This methodology features mild reaction conditions, a broad substrate scope and good functional group tolerance. (Figure presented.).
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.
Steric buttressing in the Pauson-Khand reactions of benzyl enynes
Madu, Christian E.,Dias, H.V. Rasika,Lovely, Carl J.
, p. 6118 - 6137 (2017/09/29)
The application of the intramolecular Pauson-Khand reaction of 1,n-enynes provides a convenient method for the construction of polycyclic frameworks but this process has largely been limited to the formation of 5,5- and 5,6-fused ring systems. In this report, we describe the application of the Pauson-Khand cyclization to 1,8-enynes embedded in an aromatic ring system wherein it is determined that the presence of steric buttresses in the form of t-butyl groups facilitates the cycloaddition. These reactions proceed in good yields with either thermal or oxidative activation and in the former case, the diastereoselectivities are high. An investigation of the tolerance of this cycloaddition to substitution around the 1,8-enyne demonstrates that only 2,2-disubstitution does not result in productive cyclization. Cycloadditions with hydroxyl groups at the propargylic position while leading to fused rings are compromised by side reactions leading to reduction and in some cases tautomerization. However, these byproducts are easily minimized through conversion of the hydroxyl group to the corresponding silyl ether.
Silaborative Carbocyclizations of 1,7-Enynes. Diastereoselective Preparation of Chromane Derivatives
Xiao, You-Cai,Moberg, Christina
supporting information, p. 308 - 311 (2016/02/03)
Palladium(0)-catalyzed carbocyclization of 1,7-enynes mediated by (chlorodimethylsilyl)pinacolborane proceeds with 1,8-addition of the silicon and boron functions to give functionalized cyclohexane derivatives with boron attached to the exocyclic olefin. A variety of chromane dervatives are accessible by this method. In contrast to the analogous reactions with 1,6-enynes, the configuration of the newly formed stereogenic center is controlled by a stereogenic center present in the substrate.
Straightforward synthesis of functionalized chroman-4-ones through cascade radical cyclization-coupling of 2-(allyloxy)arylaldehydes
Zhao, Jingjing,Li, Pan,Li, Xinjian,Xia, Chungu,Li, Fuwei
supporting information, p. 3661 - 3664 (2016/03/05)
A novel and direct approach to synthesize a series of phosphonate, azide and hydroxy functionalized chroman-4-ones has been developed. The cascade transformation appears to proceed through an intramolecular addition of an in situ generated acyl radical onto the alkene, followed by a selective nucleophilic radical-electrophilic radical cross coupling.
Proton-coupled electron transfer from tyrosine: A strong rate dependence on intramolecular proton transfer distance
Zhang, Ming-Tian,Irebo, Tania,Johansson, Olof,Hammarstroem, Leif
supporting information; experimental part, p. 13224 - 13227 (2011/10/10)
Proton-coupled electron transfer (PCET) was examined in a series of biomimetic, covalently linked RuII(bpy)3-tyrosine complexes where the phenolic proton was H-bonded to an internal base (a benzimidazyl or pyridyl group). Photooxidation in laser flash/quench experiments generated the RuIII species, which triggered long-range electron transfer from the tyrosine group concerted with short-range proton transfer to the base. The results give an experimental demonstration of the strong dependence of the rate constant and kinetic isotope effect for this intramolecular PCET reaction on the effective proton transfer distance, as reflected by the experimentally determined proton donor-acceptor distance.
N-heterocyclic carbene-catalyzed hydroacylation of unactivated double bonds
Hirano, Keiichi,Biju, Akkattu T.,Piel, Isabel,Glorius, Frank
supporting information; experimental part, p. 14190 - 14191 (2010/02/15)
(Chemical Equation Presented) An intramolecular N-heterocyclic carbene (NHC)-catalyzed hydroacylation of unactivated double bonds is reported. Systematic variation of the catalyst structure revealed an N- mesitylthiazolylidene annulated with a seven-membered ring to be especially reactive. This NHC enables a unique C-C bond-forming reaction to afford substituted chroman-4-ones in moderate to excellent yields, even ones containing all-carbon quaternary centers.
Steric promotion of the intramolecular Pauson-Khand reaction of aryl enynes
Madu, Christian E.,Lovely, Carl J.
, p. 2011 - 2016 (2008/02/11)
The intramolecular Pauson-Khand reaction of 1,8-enynes derived from salicylaldehyde derivatives has been investigated. Substrates derived from salicylaldehyde itself reacted poorly in this reaction, but related substrates containing ortho-tert-butyl substituents participated quite effectively and in many cases the cyclizations proceeded with high levels of diastereoselectivity. Georg Thieme Verlag Stuttgart.
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.
