[reaction: see text] The rearrangement of the carbamoyl group in allenyl carbamate 1 in the presence of n-BuLi in situ generates the allenolate 3, which is subsequently intercepted with aromatic aldehydes furnishing (Z)- or (E)-configured Baylis-Hillman-type adducts 4 or 5. The double bond isomers can be interconverted by a retro aldol-type reaction.
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http://dx.doi.org/10.1021/ol0483908 | DOI Listing |
ChemMedChem
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 PDFChem Commun (Camb)
April 2013
Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China.
A highly efficient direct asymmetric aldol addition-isomerization reaction at the α-position of α,β-unsaturated γ-butyrolactam and aryl α-ketoesters by using a bifunctional thiourea catalyst was achieved. Morita-Baylis-Hillman type adducts containing a quaternary stereocenter can be obtained in high yields and with excellent enantioselectivities (up to 99% ee).
View Article and Find Full Text PDFOrg Lett
August 2007
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan.
Barium-catalyzed direct Mannich-type reactions of a beta,gamma-unsaturated ester are described. The Ba-catalyst not only promoted the Mannich-type reactions, but also isomerized Mannich adducts to afford beta-methyl aza-Morita-Baylis-Hillman-type products in 61-88% yield from various aryl, heteroaryl, and alkyl imines. Preliminary trials on enantioselective variants with a chiral biaryldiol ligand gave products in up to 80% ee.
View Article and Find Full Text PDFJ Am Chem Soc
May 2007
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA.
Three-component coupling reactions between trialkylphosphines, methyl propiolates, and aldehydes produced 1:1:1 dipolar adducts in moderate-to-excellent yields. The product phosphonium enolate zwitterions were isolated as crystalline solids. X-ray crystallographic analyses of these single crystals established unequivocally the dipolar structures of these tetravalent phosphonium enolate zwitterions.
View Article and Find Full Text PDFOrg Lett
October 2004
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, D-48149 Münster, Germany.
[reaction: see text] The rearrangement of the carbamoyl group in allenyl carbamate 1 in the presence of n-BuLi in situ generates the allenolate 3, which is subsequently intercepted with aromatic aldehydes furnishing (Z)- or (E)-configured Baylis-Hillman-type adducts 4 or 5. The double bond isomers can be interconverted by a retro aldol-type reaction.
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