52687-81-7Relevant articles and documents
Strain-Release-Driven Friedel–Crafts Spirocyclization of Azabicyclo[1.1.0]butanes
Aggarwal, Varinder K.,Noble, Adam,Tyler, Jasper L.
supporting information, (2021/12/08)
The identification of spiro N-heterocycles as scaffolds that display structural novelty, three-dimensionality, beneficial physicochemical properties, and enable the controlled spatial disposition of substituents has led to a surge of interest in utilizing these compounds in drug discovery programs. Herein, we report the strain-release-driven Friedel–Crafts spirocyclization of azabicyclo[1.1.0]butane-tethered (hetero)aryls for the synthesis of a unique library of azetidine spiro-tetralins. The reaction was discovered to proceed through an unexpected interrupted Friedel–Crafts mechanism, generating a highly complex azabicyclo[2.1.1]hexane scaffold. This dearomatized intermediate, formed exclusively as a single diastereomer, can be subsequently converted to the Friedel–Crafts product upon electrophilic activation of the tertiary amine, or trapped as a Diels–Alder adduct in one-pot. The rapid assembly of molecular complexity demonstrated in these reactions highlights the potential of the strain-release-driven spirocyclization strategy to be utilized in the synthesis of medicinally relevant scaffolds.
Linear-selective hydroformylation of vinyl ether using Rh (acac)(2,2′-bis{(di[1H-indol-1-yl]phosphanyl)oxy}-1,1′-binaphthalene) – Possible way to synthesize 1,3-propanediol
Wan, Kefeng,Zhao, Jiangui,Qin, Song,Zheng, Xueli,Fu, Haiyan,Li, Ruixiang,Chen, Hua,Yang, Jijun,Yang, Chunji
, (2020/07/24)
Three bidentate phosphoramidite ligands were synthesized, characterized, and employed in Rh-catalyzed hydroformylation of vinyl ethers. The complex Rh(acac)(2,2′-bis{(di[1H-indol-1-yl]phosphanyl)oxy}-1,1′-binaphthalene} (acac = acetylacetone) (Rh-L4) was also synthesized and characterized. Rh-L4 showed good regioselectivity for the hydroformylation of vinyl ethers under mild reaction conditions: 2 MPa of syngas, 1:1 (H2/CO) substrate/catalyst molar ratio 1000:1, and 60 °C. The linear selectivity was up to 98%, and in most cases was about 80%, with no hydrogenation product formation observed, which could be a potential way to synthesize 1,3-propanediol. A mechanism study including density functional theory computational analysis showed that both Rh–H and CO insertion steps in the hydroformylation of vinyl ether were linear-preferred in our catalyst system.
Highly Enantioselective Hydrogenation of Amides via Dynamic Kinetic Resolution Under Low Pressure and Room Temperature
Rasu, Loorthuraja,John, Jeremy M.,Stephenson, Elanna,Endean, Riley,Kalapugama, Suneth,Clément, Roxanne,Bergens, Steven H.
supporting information, p. 3065 - 3071 (2017/03/11)
High-throughput screening and lab-scale optimization were combined to develop the catalytic system trans-RuCl2((S,S)-skewphos)((R,R)-dpen), 2-PrONa, and 2-PrOH. This system hydrogenates functionalized α-phenoxy and related amides at room temperature under 4 atm H2 pressure to give chiral alcohols with up to 99% yield and in greater than 99% enantiomeric excess via dynamic kinetic resolution.
α-Aroyloxyaldehydes: Scope and limitations as alternatives to α-haloaldehydes for NHC-catalysed redox transformations
Ling, Kenneth B.,Smith, Andrew D.
supporting information; experimental part, p. 373 - 375 (2011/02/24)
α-Aroyloxyaldehydes are readily prepared bench stable synthetic intermediates. Their ability to act as α-haloaldehyde surrogates for NHC-promoted redox esterifications and in [4+2] cycloadditions is described.
One-pot synthesis of imidazole-4-carboxylates by microwave-assisted 1,5-electrocyclization of azavinyl azomethine ylides
Preti, Lisa,Attanasi, Orazio A.,Caselli, Emilia,Favi, Gianfranco,Ori, Claudia,Davoli, Paolo,Felluga, Fulvia,Prati, Fabio
supporting information; experimental part, p. 4312 - 4320 (2010/10/21)
Diversely functionalized imidazole-4-carboxylates were synthesized by microwave-assisted 1,5-eletrocyclization of 1,2diaza-l,3-diene-derived azavinyl azomethine ylides. 1,2-Diaza-1,3-dienes were treated with primary aliphatic or aromatic amines and subjected to microwave irradiation in the presence of aldehydes. 3-Alkyl- and 3-arylimidazole-4-carboxylates were prepared in good yields through a one-pot multicomponent procedure. Modulation of the substituents at C-2, N-3, and C-5 was possible, and 2-unsubstituted imidazoles were obtained when paraformaldehyde was used.
Enantioselective synthesis of chiral β-aryloxy alcohols by asymmetric hydrogenation of a-aryloxy aldehydes via dynamic kinetic resolution
Zhou, Zhang-Tao,Xie, Jian-Hua,Zhou, Qi-Lin
supporting information; experimental part, p. 363 - 366 (2009/11/30)
A catalytic enantioselective hydrogenation of racemic α-aryloxy aldehydes via dynamic kinetic resolution has been developed by using (diamine)(spirodiphosphine)ruthenium(II) chloride [RuCl 2(SDPs)(diamine)] catalysts. Employing this new reactio
Hydroformylation of alkenes employing rhodium(I) complexes and a phosphine oxide ligand
Clark, Helen J.,Wang, Ruiping,Alper, Howard
, p. 6224 - 6225 (2007/10/03)
Following the facile synthesis of a novel phosphine oxide compound, (diphenylphosphinoyl)phenylmethanol (1), this compound was employed as a ligand in the rhodium-catalyzed hydroformylation of alkenes, with good conversions and regioselectivities. This ligand was partially resolved using an enzyme, and enantioselective hydroformylation was carried out with the addition of a rhodium(I) complex. The rhodium(I) complex containing ligand 1 was not isolated, although it was subjected to low-temperature NMR studies.
Aqueous Biphasic Hydroformylation Catalysed by Protein-Rhodium Complexes
Bertucci,Botteghi,Giunta,Marchetti,Paganelli
, p. 556 - 562 (2007/10/03)
The water-soluble complex derived from Rh(CO)2(acac) and human serum albumin (HSA) proved to be efficient in the hydroformylation of several olefin substrates. The chemoselectivity and regioselectivity were generally higher than those obtained by using the classic catalytic systems like TPPTS-Rh(I) (TPPTS= triphenylphosphine-3,3′,3″-trisulfonic acid trisodium salt). Styrene and 1-octene, for instance, were converted in almost quantitative yields into the corresponding oxo-aldehydes at 60°C and 70 atm (CO/H2=1) even at very low Rh(CO)2(acac)/HSA catalyst concentrations. The possibility of easily recovering the Rh(I) compound makes the system environmentally friendly. The circular dichroism technique was useful for demonstrating the Rh(I) binding to the protein and to give information on the stability in solution of the catalytic system. Some other proteins have been used to replace HSA as complexing agent for Rh(I). The results were less impressive than those obtained using HSA and their complexes with Rh(I) were much less stable.
A protein-rhodium complex as an efficient catalyst for two-phase olefin hydroformylation
Marchetti,Mangano,Paganelli,Botteghi
, p. 3717 - 3720 (2007/10/03)
A highly efficient and chemoselective biphasic hydroformylation of olefins was accomplished using water soluble complexes formed by the interaction between Rh(CO)2(acac) and human serum albumin (HSA), a readily available water soluble protein. A new type of shape-selectivity was observed in the hydroformylation of sterically hindered olefins. (C) 2000 Elsevier Science Ltd.
Phosphine oxides as ligands in the hydroformylation reaction
Abu-Gnim, Chalil,Amer, Ibrahim
, p. 235 - 243 (2007/10/03)
A new rhodium-phosphine oxide system has been investigated in the hydroformylation reaction. Some of the phosphine oxide ligands of type 2-12 (i.e. R2N(CH2)nP(O)R′2, R′ = Ph, Cy; n = 0, 1, 2, 3; R = Me, Et, iPr, or NR2 = 2-pyridyl) were found to be better ligands than the phosphine analogues (i.e. R2N(CH)2PR′2) in the hydroformylation of olefins catalyzed by rhodium complexes. Detailed examination of factors controlling the selectivity for aldehydes formation revealed the following characteristics of the reaction: (a) use of ligands having bulkier amino groups decrease the yield of the aldehydes slightly; (b) ligands having amino groups with low basicity decrease the rate of the hydroformylation dramatically; (c) the electronic properties of the phosphine oxide group have no influence on the hydroformylation reaction; (d) uncoordinating solvents of low polarity such as dichloromethane, chloroform and toluene gave the best reaction rate and selectivity; (e) spectroscopic investigation of the hydroformylation of styrene catalyzed by rhodium with ligand 2 shows that the ligand is coordinated by the amino and the phosphine oxide groups under 1 atm of CO-H2 and only by the amino group under 600 lbf in-2 of CO-H2.
