68975-07-5Relevant academic research and scientific papers
Design of oxa-spirocyclic PHOX ligands for the asymmetric synthesis of lorcaserin: Via iridium-catalyzed asymmetric hydrogenation
Ye, Xiang-Yu,Liang, Zhi-Qin,Jin, Cong,Lang, Qi-Wei,Chen, Gen-Qiang,Zhang, Xumu
supporting information, p. 195 - 198 (2021/01/14)
Phosphine-oxazoline (PHOX) ligands are a very important class of privileged ligands in asymmetric catalysis. A series of highly rigid oxa-spiro phosphine-oxazoline (O-SIPHOX) ligands based on O-SPINOL was synthesized efficiently, and their iridium complexes were synthesized by coordination of the O-SIPHOX ligands to [Ir(cod)Cl]2 in the presence of sodium tetrakis-3,5-bis(trifluoromethyl)phenylborate (NaBArF). The cationic iridium complexes showed high reactivity and excellent enantioselectivity in the asymmetric hydrogenation of 1-methylene-tetrahydro-benzo[d]azepin-2-ones (up to 99% yield and up to 99% ee). A key intermediate of the anti-obesity drug lorcaserin could be efficiently synthesized using this protocol.
Selective Construction of C?C and C=C Bonds by Manganese Catalyzed Coupling of Alcohols with Phosphorus Ylides
Liu, Xin,Werner, Thomas
, p. 1096 - 1104 (2020/12/31)
Herein, we report the manganese catalyzed coupling of alcohols with phosphorus ylides. The selectivity in the coupling of primary alcohols with phosphorus ylides to form carbon-carbon single (C?C) and carbon-carbon double (C=C) bonds can be controlled by the ligands. In the conversion of more challenging secondary alcohols with phosphorus ylides the selectivity towards the formation of C?C vs. C=C bonds can be controlled by the reaction conditions, namely the amount of base. The scope and limitations of the coupling reactions were thoroughly evaluated by the conversion of 21 alcohols and 15 ylides. Notably, compared to existing methods, which are based on precious metal complexes as catalysts, the present catalytic system is based on earth abundant manganese catalysts. The reaction can also be performed in a sequential one-pot reaction generating the phosphorus ylide in situ followed manganese catalyzed C?C and C=C bond formation. Mechanistic studies suggest that the C?C bond was generated via a borrowing hydrogen pathway and the C=C bond formation followed an acceptorless dehydrogenative coupling pathway. (Figure presented.).
Rhodium-Catalyzed Enantioselective Anti-Markovnikov Hydroformylation of α-Substituted Acryl Acid Derivatives
Li, Shuailong,Li, Zhuangxing,You, Cai,Li, Xiuxiu,Yang, Jiaxin,Lv, Hui,Zhang, Xumu
, p. 1108 - 1112 (2020/02/04)
Rhodium-catalyzed asymmetric anti-Markovnikov hydroformylation of α-substituted acrylates/acrylamides has been developed. By employing the Rh/(S,S)-DTBM-YanPhos complex, a series of β-chiral linear aldehydes were obtained in high yields (up to 94% yield) and high enantioselectivities (up to 96% ee). The utility of this methodology is demonstrated by a gram-scale reaction and a concise synthetic route to chiral ?3-butyrolactone.
Rhodium-catalyzed asymmetric hydrogenation of exocyclic α,β-unsaturated carbonyl compounds
Yang, Jiaxin,Li, Xiuxiu,You, Cai,Li, Shuailong,Guan, Yu-Qing,Lv, Hui,Zhang, Xumu
, p. 856 - 859 (2020/02/15)
A highly enantioselective hydrogenation of exocyclic α,β-unsaturated carbonyl compounds catalyzed by Rh/bisphosphine-thiourea (ZhaoPhos) has been developed, giving the corresponding α-chiral cyclic lactones, lactams and ketones with high yields and excellent enantioselectivities (up to 99% yield and 99% ee). Remarkably, the hydrogen bond between the substrate and the catalyst plays a critical role in this transformation. The synthetic utility of this protocol has been demonstrated by efficient synthesis of chiral 3-(4-fluorobenzyl)piperidine, a key chiral fragment of bioactive molecules.
NCP ligand, [...] complex, synthesis method, intermediate and application
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Paragraph 0122; 0210-0212, (2018/07/30)
The invention discloses an NCP ligand, iridium complex, synthetic method, intermediate and application thereof. The invention provides an NCP ligand and an NCP ligand iridium complex, wherein R1, R2, R3, R4, R5, R6 and R7 separately represent hydrogen atom or C1-C30 alkyl, R' and R'' independently represent C1-C30 alkyl. The invention provides the application of the NCP ligand iridium complex to the catalysis of alkane dehydrogenation reaction, olefin isomerization reaction, alcohol dehydrogenation reaction, ester alpha alkylation reaction, and amide alpha alkylation reaction. The NCP ligand provided by the invention contains dialkyl substituted phosphine, which has strong electron donating ability and can form a NCP ligand iridium complex by complexing with iridium. The NCP ligand iridium complex uses pyridine to replace a conventional alkyl phosphate electron donor, and has the advantages of good stability, high selectivity on alkane dehydrogenation reaction, mild reaction conditions, good catalytic effect, and industrial production prospect.
A palladium-catalyzed asymmetric allylic alkylation approach to α-quaternary γ-butyrolactones
De Oliveira, Marllon Nascimento,Fournier, Jeremy,Arseniyadis, Stellios,Cossy, Janine
supporting information, p. 14 - 17 (2017/11/27)
The Pd-catalyzed asymmetric allylic alkylation (Pd-AAA) of enol carbonates derived from γ-butyrolactones is reported, affording the corresponding enantioenriched α,α′-disubstituted γ-butyrolactones in both high yields and high enantioselectivities (up to 94% ee). This method was eventually applied to the synthesis of chiral spirocyclic compounds.
Rh-Catalyzed Conjugate Addition of Aryl and Alkenyl Boronic Acids to α-Methylene-β-lactones: Stereoselective Synthesis of trans-3,4-Disubstituted β-Lactones
Malapit, Christian A.,Luvaga, Irungu K.,Caldwell, Donald R.,Schipper, Nicholas K.,Howell, Amy R.
supporting information, p. 4460 - 4463 (2017/09/11)
A one-step preparation of 3,4-disubstituted β-lactones through Rh-catalyzed conjugate addition of aryl or alkenyl boronic acids to α-methylene-β-lactones is described. The operationally simple, stereoselective transformation provides a broad range of β-la
Novel synthesis of physovenine and physostigmine analogs
Wang,Alluri,Nikogosyan,Decarlo,Monteiro,Mabagos,Feng,White,Bartolini,Andrisano,Zhang,Ganguly
, p. 3046 - 3049 (2016/07/06)
This Letter describes a versatile synthetic approach to prepare physovenine and physostigmine analogs. A series of analogs were synthesized and evaluated for cholinesterase inhibition activities, including human acetylcholinesterase (AChE) and butyrylchol
Copper(II)-Promoted Cyclization/Difunctionalization of Allenols and Allenylsulfonamides: Synthesis of Heterocycle-Functionalized Vinyl Carboxylate Esters
Casavant, Barbara J.,Khoder, Zainab M.,Berhane, Ilyas A.,Chemler, Sherry R.
supporting information, p. 5958 - 5961 (2016/01/09)
A unique method to affect intramolecular aminooxygenation and dioxygenation of allenols and allenylsulfonamides is described. These operationally simple reactions occur under neutral or basic conditions where copper(II) carboxylates serve as reaction promoter, oxidant, and carboxylate source. Moderate to high yields of heterocycle-functionalized vinyl carboxylate esters are formed with moderate to high levels of diastereoselectivity. Such vinyl carboxylate esters could serve as precursors to α-amino and α-oxy ketones and derivatives thereof.
A General and mild catalytic α-alkylation of unactivated esters using Alcohols
Guo, Le,Ma, Xiaochen,Fang, Huaquan,Jia, Xiangqing,Huang, Zheng
supporting information, p. 4023 - 4027 (2015/03/30)
Catalytic α-alkylation of esters with primary alcohols is a desirable process because it uses low-toxicity agents and generates water as the by-product. Reported herein is a NCP pincer/Ir catalyst which is highly efficient for α-alkylation of a broad scope of unactivated esters under mild reaction conditions. For the first time, alcohols alkylate unactivated α-substituted acyclic esters, lactones, and even methyl and ethyl acetates. This method can be applied to the synthesis of carboxylic acid derivatives with diverse structures and functional groups, some of which would be impossible to access by conventional enolate alkylations with alkyl halides. In a pinch: An NCP pincer/iridium catalyst is highly efficient for the α-alkylation of unactivated esters using alcohol under mild reaction conditions. The reaction is simple, clean, and scalable (1-10 mmol), and the scope with respect to the ester is wide.
