6-Deoxyerythronolide B Synthase Thioesterase-Catalyzed Macrocyclization Is Highly Stereoselective
摘要:
Macrocyclic polyketide natural products are an indispensable source of therapeutic agents. The final stage of their biosynthesis, macrocyclization, Is catalyzed regio- and stereoselectively by a thioesterase. A panel of substrates were synthesized to test their specificity for macrocyclization by the erythromycin polyketide synthase TE (DEBS TE) in vitro. It was shown that DEBS TE is highly stereospecific, successfully macrocyclizing a 14-member ring substrate with an R configured O-nucleophile, and highly regioselective, generating exclusively the 14-member lactone over the 12-member lactone.
Chemoenzymatic asymmetric synthesis of harzia lactone A stereomers
摘要:
A facile chemoenzymatic synthesis of the harzia lactone A enantiomers was developed. A lipase-catalyzed acylation and an enantio-controlled substrate and reagent-con trol led Sharpless' asymmetric dihydroxylation are the key features of the synthesis. (C) 2009 Elsevier Ltd. All rights reserved.
Oxazoline derivatives tagged with tosylated amino acids as recyclable organocatalysts for enantioselective allylation of aldehydes
作者:Debashis Ghosh、Arghya Sadhukhan、Nabin Ch. Maity、Sayed H. R. Abdi、Noor-ul H. Khan、Rukhsana I. Kureshy、Hari C. Bajaj
DOI:10.1039/c3ra47424k
日期:——
of amino acid-based oxazoline compounds have been prepared and successfully applied to the enantioselective allylation reaction of aldehydes. The fine-tuning of the structure of the oxazolines led to (S,S)-4 as an efficient organocatalyst which gave homoallyl alcohols in good yield (up to 90%) and excellent ee (up to 99%) for a wide range of substrates including aromatic, hetero-aromatic and α,β-unsaturated
Bi(cyclopentyl)diol-Derived Boronates in Highly Enantioselective Chiral Phosphoric Acid-Catalyzed Allylation, Propargylation, and Crotylation of Aldehydes
作者:Jinping Yuan、Pankaj Jain、Jon C. Antilla
DOI:10.1021/acs.joc.0c01646
日期:2020.10.16
catalytic addition of bi(cyclopentyl)diol-derived boronates to aldehydes promoted by chiralphosphoricacids, allowing for the formation of enantioenriched homoallylic, propargylic, and crotylic alcohols (up to >99% enantiomeric excess (ee), diastereomeric ratio (dr) >20:1). These boronate substrates provided superior enantioselectivities, allowing for the reactions to proceed with low catalyst loading
Electron Transfer Initiated Heterogenerative Cascade Cyclizations: Polyether Synthesis under Nonacidic Conditions
作者:V. Satish Kumar、Danielle L. Aubele、Paul E. Floreancig
DOI:10.1021/ol0261074
日期:2002.7.1
been employed to initiate heterogenerative cascade cyclization reactions that form polyether compounds under essentially neutral conditions. The reactions proceed through mesolytic benzylic carbon-carbonbond cleavages of homobenzylic ether-derived radical cations followed by intramolecular epoxonium ionformation, leading to further cyclizations. Both oligotetrahydrofuran and tetrahydropyran structures
Asymmetric Allylboration of Aldehydes with Pinacol Allylboronates Catalyzed by 1,1′-Spirobiindane-7,7′-diol (SPINOL) Based Phosphoric Acids
作者:Chun-Hui Xing、Yuan-Xi Liao、Yimei Zhang、Darya Sabarova、Monica Bassous、Qiao-Sheng Hu
DOI:10.1002/ejoc.201101739
日期:2012.2
The asymmetricallylboration of aldehydes with pinacolallylboronates catalyzed by 1,1′-spirobiindane-7,7′-diol (SPINOL) basedphosphoricacids is described. 6,6′-Bis(2,4,6-triisopropylphenyl)SPINOL-based phosphoricacid was found to be a general, highly enantioselective catalyst for such allylboration reactions and excellent enantioselectivities were obtained for different types of aldehydes including
The HMG-CoAreductaseinhibitors, statins, are one of the most effective and bestselling cholesterol-lowering drugs. The use of statins has greatly extended people’s lives and improved the quality of their life. Development of a more efficient, stereoselective, and sustainable synthesis of statins is continuingly of utmost importance. In the present study, through screening of ketoreductases (KREDs)