- Rhodium-Catalyzed Annulation of Phenacyl Ammonium Salts with Propargylic Alcohols via a Sequential Dual C-H and a C-C Bond Activation: Modular Entry to Diverse Isochromenones
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Given their omnipresence in natural products and pharmaceuticals, isochromenone congeners are one of the most privileged scaffolds to synthetic chemists. Disclosed herein is a dual (ortho/meta) C-H and C-C activation of phenacyl ammonium salts (acylammonium as traceless directing group) toward annulation with propargylic alcohols to accomplish rapid access for novel isochromenones by means of rhodium catalysis from readily available starting materials. This operationally simple protocol features broad substrate scope and wide functional group tolerance. Importantly, the protocol circumvents the need of any stoichiometric metal oxidants and proceeds under aerobic conditions.
- Nanubolu, Jagadeesh Babu,Reddy Singam, Maneesh Kumar,Sridhar Reddy, Maddi,Suresh, Vavilapalli,Suri Babu, Undamatla
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supporting information
p. 7888 - 7893
(2021/10/25)
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- Generation, optimization and characterization of novel anti-prion compounds
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Prions are misfolded proteins involved in neurodegenerative diseases of high interest in veterinary and public health. In this work, we report the chemical space exploration around the anti-prion compound BB 0300674 in order to gain an understanding of its Structure Activity Relationships (SARs). A series of 43 novel analogues, based on four different chemical clusters, were synthetized and tested against PrPSc and mutant PrP toxicity assays. From this biological screening, two compounds (59 and 65) emerged with a 10-fold improvement in anti-prion activity compared with the initial lead compound, presenting at the same time interesting cell viability.
- Altieri, Andrea,Biasini, Emiliano,Biggi, Silvia,Ishibashi, Daisuke,Kurkin, Alexander V.,Nishida, Noriyuki,Sivtzev, Semen I.,Spiridonov, Evgeny A.
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- Synthesis of Bridged Azacycles and Propellanes via Nitrene/Alkyne Cascades
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A nitrene/alkyne cascade reaction terminating in C-H bond insertion to form functionalized bridged azacycles from carbonazidates is presented. Due to an initial Huisgen cyclization, all carbonazidates reacted with the alkyne in an exo mode in contrast to the use of sulfamate esters, which react predominately in an endo mode. Substrates with different ring sizes as well as different aryl and heteroaryl groups were also explored. Variation of the nitrene tether showed that 7-membered rings were the maximum ring size to be formed by nitrene attack on the alkyne. Examples incorporating stereocenters on the carbonazidate's tether induced diasteroselectivity in the formation of the bridged ring and two new stereocenters. Additionally, propellanes containing aminals, hemiaminals, and thioaminals formed from the bridged azacycles in the same reaction via an acid-promoted rearrangement.
- May, Jeremy A.,Wang, Qinxuan
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supporting information
p. 3039 - 3044
(2020/04/20)
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- Acid catalysed rearrangement of isobenzofurans to angularly fused phthalides
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An acid catalysed, cascade process for the construction of angularly fused polycyclic phthalides from isobenzofurans under transition metal free conditions has been reported. This process is very general for diverse gem-disubstituted isobenzofuran substrates. Control experiments supported the mechanism as the nucleophilic attack of the carboxylate onto the acid activated furan ring for the simultaneous ring closing-ring opening cascade followed by dehydration. This method serves as a greener alternative for the synthesis of angularly fused polycyclic phthalides.
- Chinta, Bhavani Shankar,Gandhi, Soniya,Baire, Beeraiah
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supporting information
p. 4715 - 4719
(2019/05/24)
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- DBU-promoted carbonylative synthesis of 1,3-oxathiolan-2-ones from propargylic alcohols with TFBen as the CO source
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A DBU-promoted carbonylative cyclization of propargylic alcohols with sulfur was developed. Various 1,3-oxathiolan-2-ones were produced in 61-98% yields under mild conditions in the absence of metal catalysts. TFBen (benzene-1,3,5-triyl triformate) as an efficient and solid CO surrogate and S8 as an ideal sulfur source were employed and incorporated.
- Ying, Jun,Zhou, Chao,Wu, Xiao-Feng
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supporting information
p. 1065 - 1067
(2018/02/22)
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- An unexpected thermal-ring-rearrangement of benzochromenes to inden-3-yl-naphthols with: P TsOH
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Described here is the first report of an unexpected thermal-ring rearrangement (TRR) of benzochromenes to indene derivatives promoted by pTsOH. This cascade ring-rearrangement proceeds through the protonation of benzochromenes by an acid catalyst followed by ring-opening and ring-closure by an intramolecular Friedel-Crafts cyclization to provide a new bicyclic framework, inden-3-yl-naphthols bearing a quaternary center, which also exhibited atropisomerism. Regioselectivity, broad substrate scope, high yields, solvent-free conditions and atom economy are the additional high points of this ring-rearrangement.
- Yaragorla, Srinivasarao,Khan, Tabassum
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supporting information
p. 7920 - 7925
(2018/11/21)
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- Asymmetric Intermolecular Heck Reaction of Propargylic Acetates and Cycloalkenes to Access Fused Cyclobutenes
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An asymmetric Heck annulation of propargylic acetates with several types of cyclic olefins affords highly strained cyclobutenes in high enantioselectivity.
- Jiao, Zhiwei,Shi, Qi,Zhou, Jianrong Steve
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supporting information
p. 14567 - 14571
(2017/10/23)
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- Microwave-Assisted Organocatalyzed Rearrangement of Propargyl Vinyl Ethers to Salicylaldehyde Derivatives: An Experimental and Theoretical Study
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The microwave-assisted imidazole-catalyzed transformation of propargyl vinyl ethers (PVEs) into multisubstituted salicylaldehydes is described. The reaction is instrumentally simple, scalable, and tolerates a diverse degree of substitution at the propargylic position of the starting PVE. The generated salicylaldehyde motifs incorporate a broad range of topologies, spanning from simple aromatic monocycles to complex fused polycyclic systems. The reaction is highly regioselective and takes place under symmetry-breaking conditions. The preparative power of this reaction was demonstrated in the first total synthesis of morintrifolin B, a benzophenone metabolite isolated from the small tree Morinda citrifolia L. A DFT study of the reaction was performed with full agreement between calculated values and experimental results. The theoretically calculated values support a domino mechanism comprising a propargyl Claisen rearrangement, a [1,3]-H shift, a [1,7]-H shift (enolization), a 6π electrocyclization, and an aromatization reaction.
- Tejedor, David,Cotos, Leandro,Márquez-Arce, Daniel,Odriozola-Gimeno, Mikel,Torrent-Sucarrat, Miquel,Cossío, Fernando P.,García-Tellado, Fernando
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supporting information
p. 18280 - 18289
(2015/12/24)
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- Mild conversion of propargylic alcohols to α,β-unsaturated enones in ionic liquids (ILs); A new 'metal free' life for the Rupe rearrangement
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A mild and selective transition metal free protocol for the conversion of propargylic alcohols to cyclic and acyclic α,β-unsaturated enones via the Rupe rearrangement is reported. The method utilizes the Br?nsted acidic ionic liquid [BMIM-SO3H][OTf] as catalyst and [BMIM][PF 6] as solvent and offers the potential for recycling and reuse of the IL solvent. The feasibility to synthesize bicyclic fused cyclopentenone derivatives via a Rupe → Aldol → Nazarov sequence utilizing this protocol has also been demonstrated.
- Nandi, Ganesh C.,Rathman, Benjamin M.,Laali, Kenneth K.
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supporting information
p. 6258 - 6263
(2013/10/22)
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- Silver-catalyzed direct addition of terminal alkynes to simple cyclic ketones in water
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The first catalytic addition of terminal alkynes to simple cyclic ketones in water catalyzed by silver was developed. Cyclic ketones were reacted with terminal alkynes efficiently in water to give the corresponding propargyl alcohols. Georg Thieme Verlag
- Jia, Zhenhua,Li, Xingshu,Chan, Alberts. C.,Li, Chao-Jun
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p. 2758 - 2762
(2013/02/21)
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- Transition metal-free stereoselective α-vinylation of cyclic ketones with arylacetylenes in the superbasic catalytic triad potassium hydroxide/tert-butyl alcohol/dimethyl sulfoxide
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A stereoselective α-vinylation of cycloaliphatic ketones with arylacetylenes under the transition metal-free conditions has been developed. The reaction is promoted by the superbasic catalytic triad potassium hydroxide/tert-butyl alcohol/dimethyl sulfoxide (80-110 °C, 1-2 h) to afford mainly (E)-β,γ-ethylenic ketones, their (E)-α,β-isomers being minor products, in up to 83% total yield. Copyright
- Trofimov, Boris A.,Schmidt, Elena Yu.,Zorina, Nadezhda V.,Ivanova, Elena V.,Ushakov, Igor A.,Mikhaleva, Al'Bina I.
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supporting information; experimental part
p. 1813 - 1818
(2012/08/13)
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- Mild and solvent-free alkynylation of ketones on the KF/alumina
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The solvent-free alkynylation of various ketones on the surface of KF/alumina under mild conditions is described. Copyright Taylor & Francis, Inc.
- Sharifi, Ali,Mirzaei, Mojtaba,Naimi-Jamal, M. Reza
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p. 1039 - 1044
(2007/10/03)
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- Poly[styrene(iodosodiacetate)]-promoted ring expansion reaction of 1-alkynylcycloalkanols: A novel synthesis of (Z)-2-(1-iodo-1-organyl) methylenecycloalkanones
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The ring expansion reaction of 1-alkynylcycloalkanols with poly[styrene(iodosodiacetate)] and iodine affords (Z)-2-(1-iodo-1-organyl) methylenecycloalkanones in moderate to good yields.
- Chen, Jiang-Min,Huang, Xian
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p. 2459 - 2462
(2007/10/03)
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- Tertiary acetylenic alcohols and diols on the basis of phenylacetylene and 2-methyl-3-butyn-2-ol
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A procedure has been proposed for the synthesis of tertiary acetylenic alcohols and diols by treatment of phenylacetylene or 2-methyl-3-butyn-2-ol with butyllithium and subsequent reaction of lithium phenylacetylide or lithium 4-lithio-2-methyl-3-butyn-2-
- Potkin,Dikusar,Kozlov
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p. 1260 - 1265
(2007/10/03)
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- Solvent-free addition of ethynylbenzene to ketones
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The addition of ethynylbenzene to ketones proceeded efficiently in the absence of a solvent to give tertiary alkynols in good yields.
- Miyamoto,Yasaka,Tanaka
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p. 185 - 186
(2007/10/03)
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- Efficient routes to cyclic 2,3-epoxyalcohols from cycloalkenyl ketones, via cycloalkenyl alcohols
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The minimising of torsional strain and non-bonding interactions is proposed as the explanation of high diastereoselectivity observed in the epoxidation of cycloalkenyl alcohols, reported for twenty three examples. The resulting 2,3-epoxyalcohols are key i
- Marson,Walker,Pickering,Harper,Wrigglesworth,Edge
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p. 10317 - 10338
(2007/10/02)
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