- Ruthenium-Catalyzed Enantioselective Hydrogenation/Lactonization of 2-Acylarylcarboxylates: Direct Access to Chiral 3-Substituted Phthalides
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Highly enantioselective tandem hydrogenation/lactonization of various 2-acylarylcarboxylates including 2-aroylarylcarboxylates were realized by using [RuCl(benzene)(S)-SunPhos]Cl as the catalyst under mild reaction conditions. Excellent enantioselectivities (up to 99.6 % ee) and activities (S/C=1000) were obtained. This convenient and practical method enables a direct access to a series of highly optically pure 3-substituted phthalides that are very important molecules as valuable pharmacological compounds and diversified synthons for medicinal chemistry. Moreover, a gram-scale reaction was performed to further demonstrate the practicality of this approach.
- Lu, Bin,Zhao, Mengmeng,Ding, Guangni,Xie, Xiaomin,Jiang, Lili,Ratovelomanana-Vidal, Virginie,Zhang, Zhaoguo
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p. 3989 - 3996
(2017/09/13)
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- P450 BM3-Catalyzed Regio- and Stereoselective Hydroxylation Aiming at the Synthesis of Phthalides and Isocoumarins
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Cytochrome P450 BM3 monooxygenases are able to catalyze the regio- and stereoselective oxygenation of a broad range of substrates, with promising potential for synthetic applications. To study the suitability of P450 BM3 variants for stereoselective benzylic hydroxylation of 2-alkylated benzoic acid esters, the biotransformation of methyl 2-ethylbenzoate, resulting in both enantiomeric forms of 3-methylphthalide, was investigated. In the case of methyl 2-propylbenzoate as a substrate the regioselectivity of the reaction was shifted towards β-hydroxylation, resulting in the synthesis of enantioenriched R- and S-configured 3-methylisochroman-1-one. The potential of P450 BM3 variants for regio- and stereoselective synthesis of phthalides and isocoumarins offers a new route to a class of compounds that are valuable synthons for a variety of natural compounds.
- Holec, Claudia,Hartrampf, Ute,Neufeld, Katharina,Pietruszka, J?rg
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p. 676 - 684
(2017/04/11)
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- Phthalides by rhodium-catalyzed ketone hydroacylation
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(Chemical Equation Presented) Phthalides are biologically relevant five-membered lactones found in herbs, fruits, and vegetables. Herein we communicate the first atom-economical approach to phthalides by using enantioselective ketone hydroacylation. In the presence of Rh[(Duanphos)]X (X = NO3, OTf, OMs), various 2-ketobenzaldehydes undergo intramolecular hydroacylation to produce phthalide products in good yields and 92-98% ee's. Our study highlights the key role counterions play in controlling both reactivity and enantioselectivity. A concise asymmetric total synthesis of the celery extract (S)-(-)-3-n-butylphthalide is also presented.
- Phan, Diem H. T.,Kim, Byoungmoo,Dong, Vy M.
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supporting information; experimental part
p. 15608 - 15609
(2010/01/30)
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