A practical and convenient method for the efficient and regio- and stereoselective ring-opening of enantiopure monosubstituted epoxides by sodium azide under hydrolytic conditions is reported. The ring-opening of enantiopure styryl and pyridyl ()-epoxides by N in hot water takes place preferentially at the internal position with complete inversion of configuration to produce ()-2-azido ethanols with up to 99% enantio- and regioselectivity, while the ()-adamantyl oxirane provides mainly the ()-1-adamantyl-2-azido ethanol in excellent yield. In general, 1,2-amino ethanols were obtained in high yield and excellent enantiopurity by the reduction of the chiral 1,2-azido ethanols with PPh in water/THF, and then converted into the Boc or acetamide derivatives.
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http://dx.doi.org/10.1016/j.tetasy.2015.12.002 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Sichuan University - Wangjiang Campus: Sichuan University, Chemistry, 29 Wangjiang Rd, 610064, Chengdu, CHINA.
Poly(lactic-co-glycolic acid) (PLGA) has been widely employed for various biomedical applications owing to its biodegradability and biocompatibility. The discovery of the stereocomplex formation between enantiomeric alternating PLGA pairs underscored its potential as high-performance biodegradable materials with diverse material properties and biodegradability. Herein, we have established a regio- and stereoselective ring-opening polymerization approach for the synthesis of stereocomplexed isoenriched alternating PLGA from racemic methyl-glycolide (rac-MG).
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Key Laboratory of Photoelectric Conversion and Utilization of Solar Energy, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
The poly(lactic-co-glycolic acid) (PLGA) with completely alternating sequence has attracted growing attention as an ideal candidate in controlled drug delivery. However, the approach to completely alternating PLGA remains a challenge. Herein, we report the successful synthesis of completely alternating PLGA via highly regioselective and stereoselective ring-opening polymerization.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY, 14853, USA.
Polymer stereocomplex formation represents a promising research area as it can improve thermal and mechanical properties of co-crystallized polymer strands of opposite chirality. Polymers that form stereocomplexes commonly feature high stereoregularity and usually require sourcing from enantiopure monomer building blocks. Herein, we report the in situ polyether stereocomplex formation from racemic epoxide monomers, i.
View Article and Find Full Text PDFMolecules
July 2024
EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST, UK.
Malamides (diamide derivatives of malic acid) are prevalent in nature and of significant biological interest, yet only limited synthetic methods to access functionalised enantiopure derivatives have been established to date. Herein, an effective synthetic method to generate this molecular class is developed through in situ formation of spirocyclic β-lactone-oxindoles (employing a known enantioselective isothiourea-catalysed formal [2+2] cycloaddition of C(1)-ammonium enolates and isatin derivatives) followed by a subsequent dual ring-opening protocol (of the β-lactone and oxindole) with amine nucleophiles. The application of this protocol is demonstrated across twelve examples to give densely functionalised malamide derivatives with high enantio- and diastereo-selectivity (up to >95:5 dr and >99:1 er).
View Article and Find Full Text PDFJ Org Chem
August 2024
Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India.
A simple one-pot, two-step strategy for the synthesis of tetrahydro-1-azepino[4,3,2-]indoles via Lewis acid-catalyzed S2-type ring opening of activated azetidines with 4-bromoindole, followed by a Pd-catalyzed intramolecular C-N cyclization reaction, with good to excellent yields is described. Utilizing this protocol, the vasopressin V2 receptor antagonist precursor has been synthesized easily. Enantioenriched tetrahydro-1-azepino[4,3,2-]indoles were obtained by starting from enantiopure azetidine.
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