- Resolution of Vaulted Biaryl Ligands via Borate Esters of Quinine and Quinidine
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Given the sudden and unexplained rise in the cost of (+)- A nd (-)-sparteine, an alternative method for the resolution of vaulted biaryls has been developed. This method involves the reaction of a racemic vaulted biaryl ligand with one equivalent of BH3·SMe2 and one equivalent of either quinine or quinidine. A precipitate then forms from the resulting mixture of diastereomeric borates as a result of differential solubilities. Hydrolysis of the precipitate then liberates the (S)-ligand in the case of quinine and the (R)-ligand in the case of quinidine, both with >99% ee. This method has been applied to 16 different vaulted biaryl ligands, including 10 whose preparation is described here for the first time. In addition, proof of principle has been demonstrated for the dynamic thermodynamic resolution of the vaulted biaryl ligands with this method in combination with a nonchiral copper(II) complex that can racemize the ligand.
- Cagnon, Brian R.,Mohammadlou, Aliakbar,Wulff, William D.,Yin, Xiaopeng,Zheng, Li
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- Dual Nickel/Photoredox-Catalyzed Deaminative Cross-Coupling of Sterically Hindered Primary Amines
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We report a method to activate α-3° amines for deaminative arylation via condensation with an electron-rich aldehyde and merge this reactivity with nickel metallaphotoredox to generate benzylic quaternary centers, a common motif in pharmaceuticals and natural products. The reaction is accelerated by added ammonium salts. Evidence is provided in support of two roles for the additive: inhibition of nickel black formation and acceleration of the overall reaction rate. We demonstrate a robust scope of amine and haloarene coupling partners and show an expedited synthesis of ALK2 inhibitors.
- Dorsheimer, Julia R.,Ashley, Melissa A.,Rovis, Tomislav
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supporting information
p. 19294 - 19299
(2021/11/23)
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- Preparation method of 4-cycloalkylacetophenone derivatives
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The invention discloses a preparation method of 4-cycloalkylacetophenone derivatives, and belongs to the technical field of organic compounds. A 2-substituted acetophenone derivative or a 3-substituted acetophenone derivative is used as an initiator, so raw materials are easy to obtain and have many kinds; and the 4-substituted cycloalkyl acetophenone derivatives obtained by using the method are various, can be directly used, and can also be used in other further reactions. The preparation method has the advantages of simplicity in reaction operation and post-treatment, high yield, and no generation of a large amount of metal salts, is a green method with high atom economy, and is suitable for large-scale production.
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Paragraph 0078-0080
(2019/01/08)
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- Enabling the Cross-Coupling of Tertiary Organoboron Nucleophiles through Radical-Mediated Alkyl Transfer
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The construction of quaternary centers is a common challenge in the synthesis of complex materials and natural products. Current cross-coupling strategies that can be generalized for setting these centers are sparse and, when known, are typically predicated on the use of reactive organometallic reagents. To address this shortcoming a new, photoredox-Ni dual catalytic strategy for the cross-coupling of tertiary organoboron reagents with aryl halides is reported. In addition to details on the cross-coupling scope and limitations, full screening efforts and mechanistic experiments are communicated.
- Primer, David N.,Molander, Gary A.
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supporting information
p. 9847 - 9850
(2017/08/02)
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- Synthesis of substituted adamantylzinc reagents using a Mg-insertion in the presence of ZnCl2 and further functionalizations
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The LiCl-mediated Mg-insertion in the presence of ZnCl2 allows an efficient synthesis of adamantylzinc reagents starting from the corresponding functionalized tertiary bromides. The highly reactive adamantylzinc species readily undergo a broad
- Saemann, Christoph,Dhayalan, Vasudevan,Schreiner, Peter R.,Knochel, Paul
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supporting information
p. 2418 - 2421
(2014/05/20)
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- Pyridinium N-phenoxide betaines and their application to the determination of solvent polarities, XXIV. Syntheses and UV-vis spectroscopic properties of new lipophilic tert-butyl- and 1-adamantyl substituted, negatively solvatochromic pyridinium N-phenolate betaine dyes
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Syntheses and negative solvatochromism of two new lipophilic pentaphenyl pyridinium N-phenolate betaine dyes, substituted with seven tert-butyl groups (9) or with three tert-butyl and two 1-adamantyl groups (13) in the peripheral phenyl rings, are described in order to get zwitterionic dyes that are more soluble in nonpolar solvents such as the standard betaine dye, 1, which has been used for the construction of an empirical scale of solvent polarity, called the E(T)(30) scale.
- Reichardt, Christian,L?bbecke, Stefan,Mehranpour, Abdol Mohammed,Sch?fer, Gerhard
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p. 686 - 694
(2007/10/03)
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- SYNTHESIS OF 3-(ALKYLARYL)-1-ADAMANTANOLS
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The possibility was demonstrated for removal of hydride ions from 1-(alkylaryl)adamantanes by tertiary carbocations generated from the corresponding alcohols or halides in trifluoroacetic acid leading to the formation of 3-(alkylaryl)-1-adamantanols in 40-60percent yield.In the case of 1-phenyladamantane, the major product is 1-(1-adamantyl)-4-benzene formed in 71percent yield due to presence of two reaction sites (the benzene ring para position and the tertiary carbon atom of the adamantane fragment) in the starting 1-phenyladamantane.
- Kovalev, V. V.,Knyazeva, I. V.,Shokova, E. A.
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p. 692 - 696
(2007/10/02)
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