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Dr. Subramani Rajkumar Mengyao Tang Prof. Dr. Xiaoyu Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(6):2353-2357
An efficient method for the asymmetric synthesis of 4H-3,1-benzoxazines was developed by kinetic resolution of 2-amido benzyl alcohols using chiral phosphoric acid catalyzed intramolecular cyclizations. A broad range of benzyl alcohols (both secondary and tertiary alcohols) were kinetically resolved with high selectivities, with an s factor of up to 94. Mechanistic studies were performed to elucidate the mechanism of these reactions, wherein the amide moieties reacted as the electrophiles. Gram-scale reaction and facile transformations of the chiral products demonstrate the potential of this method in asymmetric synthesis of biologically active chiral heterocycles. 相似文献
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Jia-Hong Wu Siqiang Fang Xingtao Zheng Jiajia He Yi Ma Prof. Dr. Zhishan Su Prof. Dr. Tianli Wang 《Angewandte Chemie (International ed. in English)》2023,62(49):e202309515
The catalytic asymmetric synthesis of phosphorus-containing helicenes remains a formidable challenge, presumably due to the lack of rational design of substrates, right choice of reactions together with highly effective catalysis systems. Herein, we disclosed an efficient and practical DKR-involving (dynamic kinetic resolution) cascade strategy toward synthesizing a novel family of phosphorus-installing helicenes by peptide-mimic phosphonium salt (PPS) catalysis. The sequential process of PPS-catalyzed phospha-Michael attack and copper salt-facilitated aromatization led to the formation of unprecedented phosphorus-containing oxa[5]helicene scaffolds. A wide variety of substrates bearing an assortment of functional groups were compatible with this protocol, furnishing the expected helical compounds in high yields and excellent stereoselectivities. Additionally, the helical products could be conveniently elaborated to promising phosphine ligands with perfectly retained helical chirality, which turned out to be highly efficient chiral ligands in transition metal-catalyzed reactions. These findings not only expand the current library of phosphorus-containing helicenes but also offer insights to explore other challenging scaffolds with molecular chirality. 相似文献
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Enantiodivergent Atroposelective Synthesis of Chiral Biaryls by Asymmetric Transfer Hydrogenation: Chiral Phosphoric Acid Catalyzed Dynamic Kinetic Resolution 下载免费PDF全文
Prof. Dr. Keiji Mori Tsubasa Itakura Prof. Dr. Takahiko Akiyama 《Angewandte Chemie (International ed. in English)》2016,55(38):11642-11646
Reported herein is an enantiodivergent synthesis of chiral biaryls by a chiral phosphoric acid catalyzed asymmetric transfer hydrogenation reaction. Upon treatment of biaryl lactols with aromatic amines and a Hantzsch ester in the presence of chiral phosphoric acid, dynamic kinetic resolution (DKR) involving a reductive amination reaction proceeded smoothly to furnish both R and S isomers of chiral biaryls with excellent enantioselectivities by proper choice of hydroxyaniline derivative. This trend was observed in wide variety of substrates, and various chiral biphenyl and phenyl naphthyl adducts were synthesized with satisfactory enantioselectivities in enantiodivergent fashion. The enantiodivergent synthesis of synthetically challenging, chiral o‐tetrasubstituted biaryls were also accomplished, and suggests high synthetic potential of the present method. 相似文献
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Jiang Wang Pan‐Lin Shao Xin Lin Baode Ma Jialin Wen Xumu Zhang 《Angewandte Chemie (International ed. in English)》2020,59(41):18166-18171
An unprecedented Ir/f‐amphox‐catalyzed asymmetric hydrogenation of racemic 2,3‐syn‐dihydroxy‐1,4‐diones is presented involving dynamic kinetic resolution, which produces (1R,2R,3R,4R)‐tetraols. This protocol constitutes an efficient and straightforward approach to accessing sugar alcohols bearing four contiguous stereocenters. The strategy exhibits various advantages over existing methods, including excellent yields (up to 98 %), exceptional stereoselectivities (up to 99:1 dr, 99.9 % ee), operational simplicity and substrate generality. Moreover, the nature of the reaction was revealed as a stepwise transformation by in situ Fourier‐transform infrared spectroscopy and isolation of intermediates. 相似文献
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Catalytic Enantioselective Reduction of Prochiral Ketones with Chiral Ferrocenyl Amino Alcohols 总被引:1,自引:0,他引:1
The asymmetric reduction of prochiral ketones was catalyzed by a class of recoverable and highly stable chiral ferrocenyl amino alcohols derived from natural amino acids to yield optically active secondary alcohols in high chemical yields and moderate to good enantiomeric excesses. 相似文献
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<正>手性醇是一类非常重要的手性化合物,它是合成手性药物、天然产物等的重要中间体。酮的不对称催化氢化反应是合成手性醇的最为经济且环境友好的方法之一,目前已经发展了很多用于酮的不对称氢化反应的手性催化剂,但是,真正高效的手性催化剂还很少。我们在研究酮的不对称催化氢化反应过程中,发现手 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(9):2494-2498
Axially chiral cyclohexylidene oxime ethers exhibit unique chirality because of the restricted rotation of C=N. The first catalytic enantioselective synthesis of novel axially chiral cyclohexylidene oximes has been developed by catalytic desymmetrization of 4‐substituted cyclohexanones with O‐arylhydroxylamines and is catalyzed by a chiral BINOL‐derived strontium phosphate with excellent yields and good enantioselectivities. In addition, chiral BINOL‐derived phosphoric acid catalyzed dynamic kinetic resolution of α‐substituted cyclohexanones has been performed and yields versatile intermediates in high yields and enantioselectivities. 相似文献
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This work demonstrates an efficient way to prepare chiral propargylic alcohols by asymmetric addition of terminal Zn-acetylide to aldehydes catalyzed by bifunctional zinc-based complexes. The corresponding products with moderate to good yields and enantioselectivities were obtained in the absence of moisture-sensitive Ti(O i Pr)4. 相似文献
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《中国化学》2018,36(7):587-593
An organocatalytic approach for direct conversion of racemic diarylmethanols to valuable chiral diarylmethylamines is described. Different from the previously reported elegant “borrowing hydrogen” approach, the present process employs a distinct complementary formal SN1 strategy. This approach enjoys excellent enantioselectivity, mild conditions, broad scope, and easy product derivatization. Mechanistically, control experiments also provided important insights into some notable features, such as substrate kinetic resolution and reversibility as well as the critical role of the ortho‐ hydroxy group in the substrate. 相似文献
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Synergistic Kinetic Resolution and Asymmetric Propargyl Claisen Rearrangement for the Synthesis of Chiral Allenes 下载免费PDF全文
Yangbin Liu Prof. Dr. Xiaohua Liu Haipeng Hu Jing Guo Yong Xia Dr. Lili Lin Prof. Dr. Xiaoming Feng 《Angewandte Chemie (International ed. in English)》2016,55(12):4054-4058
The asymmetric propargyl Claisen rearrangement provides a convenient entry to chiral allene motifs. Herein, we describe the development of a kinetic resolution and asymmetric rearrangement of racemic propargyl vinyl ethers. This transformation afforded chiral allene products along with the enantiomerically enriched substrate in good yields with excellent diastereo‐ and enantioselectivity. The complete chirality transfer and facially selective rearrangement enabled the simultaneous construction of an axially chiral allenic unit and a quaternary carbon stereocenter. 相似文献
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利用脂肪酶催化的不对称转酯反应成功远程拆分具有季碳手性中心的西酞普兰中间体4-[4-(二甲基氨基)-1-(4’-氟苯基)-1-羟基丁基]-3-(羟基甲基)苄腈(1). 以乙酸乙烯酯作为酰基供体, 通过筛选酶和溶剂, 确定最佳脂肪酶及溶剂分别为Candida antarctica lipase B (Novozym 435)和乙腈; 并在该反应体系中考察了反应温度、二醇1与酰基供体的比例、酶浓度和摇床转速等对反应的影响, 确定优化的反应条件为: 温度30 ℃, 二醇1与酰基供体的物质的量比为1∶5, 酶浓度为10 mg/mL, 摇床转速200 r/min. 分别考察二醇1浓度为60和180 mmol/L的反应情况, 均具有较高的选择性和反应速度. 实验结果表明酶能够多次重复利用. 相似文献
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Dynamic Kinetic Resolution Approach for the Asymmetric Synthesis of Tetrahydrobenzodiazepines Using Transfer Hydrogenation by Chiral Phosphoric Acid 下载免费PDF全文
Kosaku Horiguchi Eri Yamamoto Dr. Kodai Saito Prof. Dr. Masahiro Yamanaka Prof. Dr. Takahiko Akiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8078-8083
Asymmetric synthesis of tetrahydrobenzodiazepines was achieved by transfer hydrogenation of dihydrobenzodiazepines with benzothiazoline having a hydrogen‐bonding donor substituent by means of a newly synthesized chiral phosphoric acid. This method was applicable to various racemic dihydrobenzodiazepines to give the corresponding products in good yields with excellent diastereoselectivities and enantioselectivities taking advantage of the dynamic kinetic resolution. Furthermore, the effect of bulky substituent at 3,3′‐position on the catalyst and hydrogen‐bonding donor substituent on benzothiazoline was fully elucidated by the theoretical study. 相似文献
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Our Odyssey with Functionalized Chiral Phosphines: From Optical Resolution to Asymmetric Synthesis to Catalysis 下载免费PDF全文
Our journey in organophosphorus research over the past 26 years is compiled in this Personal Account. Advances in palladacycle design have engendered a shift in our focus from template‐mediated transformations to catalysis for the direct preparation of chiral phosphines containing a wide variety of functional groups. Novel approaches to access previously inaccessible phosphines and their applications in cancer research are summarized herein.
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(S)-(1-Benzylpyrrolidin-2-yl)diphenylmethanol and cinchonine were evaluated as promotors in the asymmetricadditions of phenylacetylene to ketones,in order to prepare chiral propargylic alcohols.Good yields(up to 89%)and moderate enantioselectivities(up to 77.9% ee)were achieved.Addition of Ti(OPr-i)_4 can significantly improvethe enantioselectivity of the reaction. 相似文献