The use of a catalytic amount of platinum complexes (1 mol %) was found to be compatible with different organocatalysts (DABCO or the Jørgensen-Hayashi catalyst) that were used in the functionalization of various activated methylenes. By this method, a series of lactones with C-3 quaternary centers and substitution at C-5 were prepared.
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http://dx.doi.org/10.1021/jo2013077 | DOI Listing |
Chem Commun (Camb)
October 2020
Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, P. R. China.
We have developed a DPPE-catalyzed three molecular two component tandem reaction of γ-substituted allenoate and CS2 to construct 2-thineyl vinyl sulfide through phosphine catalyzed [3+2] cyclization followed by Michael addition. The synthetic value of the 2-thineyl vinyl sulfide was demonstrated by a concise synthesis of an anti-glaucoma agent.
View Article and Find Full Text PDFJ Org Chem
October 2020
Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, P. R. China.
Herein, we report a convenient organocatalytic asymmetric tandem cyclization/Michael addition protocol for the synthesis of diastereomerically pure and highly enantioenriched perfluoroalkyl-containing ,-acetal derivatives starting from racemic -perfluoroacyl amino acids under mild conditions. This efficient atom economic reaction leads to highly enantioselective and diastereoselective construction of ,-acetal derivatives containing oxazolone and perfluoroalkyl moieties containing vicinal quaternary and tertiary stereocenters (up to 97% yield, up to 96% ee, and up to >20:1 dr).
View Article and Find Full Text PDFOrg Lett
July 2015
School of Chemistry, University of Hyderabad, Gachibowli, Hyderabad 500046, India.
A new protocol has been developed for the synthesis of indene derivatives in a diastereoselective manner from o-alkenylbenzaldehydes and enolizable ketones in the presence of trimethyl orthoformate and catalytic triflic acid. This method involves tandem in situ formed acetal-assisted Claisen-Schmidt condensation followed by 5-exo-trig cyclization/Michael addition in one-pot. It has also been shown that the chalcones derived from o-alkenylbenzaldehydes and ketones can effectively be transformed into indene derivatives in the presence of TfOH catalyst alone.
View Article and Find Full Text PDFJ Org Chem
September 2011
Departamento de Química Orgánica (C-1), Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco 28049-Madrid, Spain.
The use of a catalytic amount of platinum complexes (1 mol %) was found to be compatible with different organocatalysts (DABCO or the Jørgensen-Hayashi catalyst) that were used in the functionalization of various activated methylenes. By this method, a series of lactones with C-3 quaternary centers and substitution at C-5 were prepared.
View Article and Find Full Text PDFJ Am Chem Soc
April 2006
Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
The first examples of a tandem Nazarov cyclization/Michael addition process are described. The sequence is efficiently catalyzed by Ir[Me(CO)(dppe)(DIB)]2+ and occurs with high diastereoselectivity, creating three contiguous stereocenters. The mechanistic factors controlling the reactivity and diastereoselectivity are discussed.
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