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Engineered enzymes for enantioselective nucleophilic aromatic substitutions.
Nature
January 2025
Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK.
Nucleophilic aromatic substitutions (SAr) are amongst the most widely used processes in the pharmaceutical and agrochemical industries, allowing convergent assembly of complex molecules through C-C and C-X (X = O, N, S) bond formation. SAr reactions are typically carried out using forcing conditions, involving polar aprotic solvents, stoichiometric bases and elevated temperatures, which do not allow for control over reaction selectivity. Despite the importance of SAr chemistry, there are only a handful of selective catalytic methods reported that rely on small organic hydrogen-bonding or phase-transfer catalysts.
View Article and Find Full Text PDFTotal synthesis of linear lipodepsipeptide kavaratamide A and its C25-epimer.
Org Biomol Chem
January 2025
Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune-411008, India.
We report the stereoselective total synthesis of kavaratamide A, a linear lipodepsipeptide from the cyanobacterium (collected in Kavaratti, India), and its unnatural C25-epimer. The convergent approach employs Keck asymmetric allylation to construct the chiral β-hydroxy carboxylic acid fragment [(3)-HDA; 3-hydroxydecanoic acid], while the peptide unit was assembled from L-Val, -Me-L-Ala, ()-Hiva, and ()-Pr--Me-pyr using well-orchestrated coupling methods to prevent racemization. Modifications to the Keck allylation conditions enabled the synthesis of the C25-epimer with good yield.
View Article and Find Full Text PDFCatalytic Asymmetric Total Synthesis of (+)-Chamaecydin and (+)-Isochamaecydin and their Stereoisomers.
Angew Chem Int Ed Engl
January 2025
Jilin Province Key Lab of Green Chemistry and Process, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin, 130022, China.
A modular approach was developed for the first catalytic asymmetric total syntheses of naturally occurring C terpene quinone methides and their non-natural stereoisomers, which feature the presence of an unprecedented spiro[4.4]nonane-containing 6-6-6-5-5-3 hexacyclic skeleton. Resting on a chiral phosphinamide-catalyzed enantioselective reduction of 2,2-disubstituted cyclohexane-1,3-dione, a concise route for the synthesis of enantioenriched 6-6 bicyclic fragment was developed.
View Article and Find Full Text PDFSynthesis of the conjugation ready tetrasaccharide repeating unit of the O-polysaccharide from Halomonas fontilapidosi KR26.
Carbohydr Res
December 2024
Sweet Lab, Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, Nadia, 741246, India. Electronic address:
Synthesis of the tetrasaccharide repeating unit of the O-polysaccharide from Halomonas fontilapidosi KR26 was accomplished through a convergent [2 + 2]-block strategy using rationally protected monosaccharide synthons derived from commercially available sugars. The target tetrasaccharide was synthesized in the form of its 2-azidoethyl glycoside to ensure further conjugation with specific aglycons without hampering the reducing end stereochemistry. Use of only acyl/aryl protecting groups was targeted to keep the terminal azido-group intact for the utilization of "Click chemistry" for further conjugations.
View Article and Find Full Text PDFCopper-Catalyzed Regio-, Diastereo-, and Enantioselective Allylic Alkylation with 1,1-Diborylalkanes.
J Am Chem Soc
December 2024
Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.
We report a copper-catalyzed regio-, diastereo-, and enantioselective allylic alkylation of allyl bromides using 1,1-diborylalkanes as prochiral nucleophiles. This methodology employs copper(I) bromide as a catalyst, an ()-BINOL-derived phosphoramidite as a ligand, and lithium benzoate as a crucial additive. The reaction affords enantioenriched homoallylic boronic esters possessing vicinal stereocenters in good yields and high diastereo- and enantioselectivity.
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