- Amide/Ester Cross-Coupling via C-N/C-H Bond Cleavage: Synthesis of β-Ketoesters
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Activated primary, secondary, and tertiary amides were coupled with enolizable esters in the presence of LiHMDS to obtain good yields of β-ketoesters at room temperature. Notably, this protocol provides an efficient, mild, and high chemoselectivity method
- Chen, Jiajia,Joseph, Devaneyan,Xia, Yuanzhi,Lee, Sunwoo
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p. 5943 - 5953
(2021/04/02)
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- Desymmetrization of meso-dicarbonatecyclohexene with β-Hydrazino carboxylic esters via a Pd-catalyzed allylic substitution cascade
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The desymmetrization of meso-dicarbonatecyclohexene with β-hydrazino carboxylic esters has been achieved via a RuPHOX/Pd-catalyzed allylic substitution cascade for the construction of chiral hexahydrocinnoline derivatives with high performance. Mechanistic studies reveal that the reaction exploits a pathway different from that of our previous work and that the first nitrogen nucleophilic process is the rate-determining step. The protocol could be conducted on a gram scale without any loss of catalytic behavior, and the corresponding chiral hexahydrocinnolines can undergo diverse transformations.
- Xu, Kai,Zheng, Yan,Ye, Yong,Liu, Delong,Zhang, Wanbin
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supporting information
p. 8836 - 8841
(2020/11/30)
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- General [4 + 1] Cyclization Approach to Access 2,2-Disubstituted Tetrahydrofurans Enabled by Electrophilic Bifunctional Peroxides
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A general [4 + 1] cyclization reaction of carbonyl nucleophiles with 2-iodomethylallyl peroxides, which function as unique electrophilic oxygen synthons, for the synthesis of a broad range of 2,2-disubstituted tetrahydrofurans is achieved under operationally simple conditions. The unprecedented asymmetric version of such reaction is also realized via chiral auxiliary-assisted cyclization, thus providing a distinct approach to access chiral tetrahydrofurans with high diastereoselectivities. The new method can be applied to the synthesis of core structure of posaconazole drug.
- Gao, Min,Zhao, Yukun,Zhong, Chen,Liu, Shengshu,Liu, Pengkang,Yin, Qi,Hu, Lin
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supporting information
p. 5679 - 5684
(2019/08/01)
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- Regioselective Synthesis of Dihydrothiophenes and Thiophenes via the Rhodium-Catalyzed Transannulation of 1,2,3-Thiadiazoles with Alkenes
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A method for the regioselective synthesis of a wide range of dihydrothiophenes was developed from the rhodium-catalyzed transannulation of 1,2,3-thiadiazoles with aliphatic, aromatic, and heteroaromatic alkenes. Tandem rhodium-catalyzed transannulation of 1,2,3-thiadiazoles with alkenes followed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) oxidation was also demonstrated for the one-pot regioselective synthesis of various thiophenes. Advantages of the present method include a broad substrate scope, wide functional group compatibility, and high regioselectivity.
- Son, Jeong-Yu,Kim, Jonghye,Han, Sang Hoon,Kim, Sung Hong,Lee, Phil Ho
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supporting information
p. 5408 - 5411
(2016/11/06)
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- Milbemycin Synthesis: Synthesis of a Macrocyclic Analogue of Non-Aromatic β-Milbemycins
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Stereoselective base-catalysed addition of the keto ester 15 and 3-methylbut-3-en-2-one gave the hydroxycyclohexanone 16.Reduction and methylation gave the monomethyl ether 23, which was regioselectivity converted into the butenolide 25 by oxidation using bromine in methanol and hydrolysis of the mixture of intermediate dimethoxydihydrofurans 24.Bromination of the butenolide 25 followed by hydrolysis gave the hydroxybutenolide 40 which was condensed with the ylide generated from the phosphonium salt 62 to give the conjugated dienes 63 and 64.Treatment with a trace of iodine induced (Z)- to (E)-isomerisation of the 10,11-double bond, and ester exchange under basic conditions with 2-(trimethylsilyl)ethanol followed by esterification with diazomethane gave the diesters 67 and 70.Deprotection gave a mixture of the hydroxy acids 71 and 72, and the hydroxy acid 71 was cyclised to give the macrolide 73.Reduction of the methyl ester gave the alcohol 74, a macrocyclic analogue of non-aromatic β-milbemycins.
- Hughes, Mark J.,Thomas, Eric J.
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p. 1493 - 1506
(2007/10/02)
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