- Enantioselective catalyses; 126:1 Axially chiral N,N-Ligands with binaphthyl/bipyridyl structure
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N,N-Ligands with combined binaphthyl/bipyridyl structure were synthesized by palladium-catalyzed coupling of 1-naphthylboronic acids with 1-halogenoisoquinoline derivates and with 4-bromo-2-(2-pyridyl)naphtho[2,3- d]-1,3-oxazole. Racemic 1-(2-methoxy-1-naphthyl)-3-(2-pyridyl)isoquinoline was resolved via diastereomeric salt formation with (-)-3-bromocamphor-8- sulfonic acid and the absolute configuration was determined by X-ray analysis.
- Brunner,Olschewski,Nuber
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- Atropisomerism of 2,2′-binaphthalenes
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The synthesis of diastereo-enriched substituted (4S)-4-isopropyl-2-(2,2′-binaphthalen-1-yl)-4,5-dihydrooxazoles from substituted 2-naphthalenylmagnesium bromides and (4S)-4-isopropyl-2-(2-methoxynaphthalen-1-yl)-4,5-dihydrooxazole (4) and (4S)-4-isopropyl-2-(2,3-dimethoxynaphthalen-1-yl)-4,5-dihydrooxazole (5) is described. The product oxazolines were converted into a number of derivatives and the free energy barriers to internal rotation of several of these derivatives were determined. The determination of the X-ray crystal structures and the c.d. spectra of (S,1S)-N-[2-hydroxy-1-(isopropyl)ethyl]-3-methoxy-1′,N-dimethyl-2,2′ -binaphthalene-1-carboxamide (22) and (R,4S)-4-isopropyl-3-methyl-2-(1′,2′,4′-trimethyl-2,2′-b inaphthalen-1-yl)-4,5-dihydrooxazolium iodide (38) allowed the assignment of the absolute configurations of all the synthetic 2,2′-binaphthalenes by comparison of their c.d. spectra with those of compounds (22) and (38).
- Baker,Brkic,Sargent,Skelton,White
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- Catalytic Enantioselective Synthesis of Axially Chiral Diarylmethylidene Indanones
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We describe the first atropselective Suzuki-Miyaura cross-coupling of β-keto enol triflates to access axially chiral (Z)-diarylmethylidene indanones (DAIs). The chemical, physical, and biological properties of DAIs are unknown, despite their being structurally similar to arylidene indanones, primarily due to the lack of racemic or chiral methods. Through this work, we demonstrate a general and efficient protocol for the racemic as well as the atropselective synthesis of (Z)-DAIs. An unusual intramolecular Morita-Baylis-Hillman reaction is utilized for the Z-selective synthesis of β-keto enol triflates.
- Kumar, Prashant,Shirke, Rajendra P.,Yadav, Sonu,Ramasastry
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p. 4909 - 4914
(2021/06/30)
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- Practical, mild and efficient electrophilic bromination of phenols by a new I(iii)-based reagent: The PIDA-AlBr3 system
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A practical electrophilic bromination procedure for phenols and phenol-ethers was developed under efficient and very mild reaction conditions. A broad scope of arenes was investigated, including the benzimidazole and carbazole core as well as analgesics such as naproxen and paracetamol. The new I(iii)-based brominating reagent PhIOAcBr is operationally easy to prepare by mixing PIDA and AlBr3. Our DFT calculations suggest that this is likely the brominating active species, which is prepared in situ or isolated after centrifugation. Its stability at 4 °C after preparation was confirmed over a period of one month and no significant loss of its reactivity was observed. Additionally, the gram-scale bromination of 2-naphthol proceeds with excellent yields. Even for sterically hindered substrates, a moderately good reactivity is observed.
- Satkar, Yuvraj,Ramadoss, Velayudham,Nahide, Pradip D.,García-Medina, Ernesto,Juárez-Ornelas, Kevin A.,Alonso-Castro, Angel J.,Chávez-Rivera, Ruben,Jiménez-Halla, J. Oscar C.,Solorio-Alvarado, César R.
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p. 17806 - 17812
(2018/05/28)
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