The N-tosyl carbamates 4a-e, easily prepared starting from the Baylis-Hillman adducts 3a-e, underwent cyclization carried out with I(2)/NIS in the presence of NaH, to give the corresponding 2-oxo-1,3-oxazolidines 5a-e in good yield and total stereoselection when the substituent at C-5 is Ar. After the removal of tosyl group, followed by the cleavage of the heterocyclic ring, the alpha-methyl-alpha-amino acids 8a,b and 10 were obtained in good yield as hydrochlorides.
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http://dx.doi.org/10.1007/s00726-009-0465-y | DOI Listing |
Org Lett
December 2024
Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China.
Highly enantioselective allylic amination and alkylation of racemic sterically hindered aryl-substituted Morita-Baylis-Hillman (MBH) adducts have been achieved by using an in situ formed Pd-catalyst from an axially chiral phenanthroline ligand. This dynamic kinetic asymmetric transformation (DYKAT) is compatible with cyclic and acyclic secondary amines, dialkyl malonates, β-keto esters, acetylacetone, and malononitrile, affording the corresponding chiral products, such as β-amino acid esters, in up to 95% yield and with up to a 99:1 enantiomeric ratio.
View Article and Find Full Text PDFChemMedChem
December 2024
School of Chemistry, University College Dublin, Dublin, D04 N2E2, Ireland.
Inspired by the cyclopentenone family of prostaglandins, a series of 4-aza, cross-conjugated cyclopentenones is described. Synthesised from N-protected (4R)-aza-cyclopentenone 5, the exocyclic alkene was installed using a modified Baylis-Hillman type aldol reaction, whereby carbon-carbon bond formation is accompanied by dehydration. In this manner octanal and octenal, for example, can be introduced to mimic the ω-group present in the natural prostaglandins.
View Article and Find Full Text PDFChemistryOpen
November 2024
Bio-Organic Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
The major threat to public health due to the outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has been recognised as a global issue. The increase in morbidity is primarily due to the lack of SARS-CoV-2 specific drugs. One of the major strategies to combat this threat is to deactivate the enzymes responsible for the replication of corona virus.
View Article and Find Full Text PDFACS Omega
November 2024
Department of Chemistry, Federal University of Paraíba, Campus I, João Pessoa, Paraíba 58051-900, Brazil.
This work shows the synthesis of a series of Morita-Baylis-Hillman adducts from isatin derivatives via an efficient green approach involving the use of a new catalyst system, a mixture of copper-manganese iminodiacetate 1D coordination polymer (Cu/Mn-IDA) and choline chloride-urea deep eutectic solvent (ChCl/urea 1:2). The adducts were obtained in good to excellent yields (59-97%) with shorter reaction times. The results demonstrate for the first time the synergistic catalytic effect of the combination of deep eutectic solvent and coordination polymer on the Morita-Baylis-Hillman reactions.
View Article and Find Full Text PDFZ Naturforsch C J Biosci
November 2024
Department of Chemistry, COMSATS University Islamabad Campus, 45550, Islamabad, Pakistan.
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