Stereoselective Synthesis of Steroids and Related Compounds, V. Synthesis of (±)-Chokol A by a Tandem Michael-Addition/Dieckmann Cyclization

1994 ◽  
Vol 1994 (9) ◽  
pp. 885-890 ◽  
Author(s):  
Ulrich Groth ◽  
Wolfgang Halfbrodt ◽  
Thomas Köhler ◽  
Paul Kreye
Synthesis ◽  
2019 ◽  
Vol 51 (17) ◽  
pp. 3356-3368
Author(s):  
Piotr Pomarański ◽  
Zbigniew Czarnocki

The synthesis of novel l-prolinal dithioacetal and its application as an organocatalyst for the direct Michael addition of cyclic ketones and acetophenone derivatives to trans-β-nitrostyrene and related compounds is described. The prolinal dithioacetal acts as effective catalyst in the case of cyclic ketones of different ring size, in particular five- and six-membered examples, as well as larger and smaller ring systems. High enantioselectivity and diastereoselectivity is observed for different substrates and trans-β-nitrostyrenes. Also, the first asymmetric syntheses of selected 2-methyl-4-nitro-1,3-diphenylbutan-1-one derivatives by application of the obtained organocatalyst is presented.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Marthe Carine Djuidje Fotsing ◽  
Dieudonné Njamen ◽  
Zacharias Tanee Fomum ◽  
Derek Tantoh Ndinteh

Abstract Cyclic and polycyclic compounds containing moieties such as imidazole, pyrazole, isoxazole, thiazoline, oxazine, indole, benzothiazole and benzoxazole benzimidazole are prized molecules because of the various pharmaceutical properties that they display. This led Prof. Landor and co-workers to engage in the synthesis of several of them such as alkylimidazolenes, oxazolines, thiazolines, pyrimidopyrimidines, pyridylpyrazoles, benzoxazines, quinolines, pyrimidobenzimidazoles and pyrimidobenzothiazolones. This review covers the synthesis of biologically active heterocyclic compounds by the Michael addition and the double Michael addition of various amines and diamines on allenic nitriles, acetylenic nitriles, hydroxyacetylenic nitriles, acetylenic acids and acetylenic aldehydes. The heterocycles were obtained in one step reaction and in most cases, did not give side products. A brief discussion on the biological activities of some heterocycles is also provided.


1990 ◽  
Vol 68 (11) ◽  
pp. 1917-1922 ◽  
Author(s):  
Réjean Ruel ◽  
Pierre Deslongchamps

The total synthesis of the title compound 22 and methyl 14α-hydroxy-5β,13α,8-androstene-1,7,17-trioxo-10β-oate 21 isomer is reported. We also describe the 1,6-Michael addition of 2-methyl-1,3-cyclopentanedione on dienone 14 and the protic ammonium salt catalyzed intramolecular Michael addition of cyclic β-ketoester on the conjugated acetylenic ketone 13. Keywords: cardenolides, steroid synthesis, aldol, Michael addition.


2017 ◽  
Vol 36 (2-3) ◽  
pp. 100-110
Author(s):  
Prashanth Thodupunuri ◽  
Marumamula Hanumaiah ◽  
Shobanbabu Bommagani ◽  
Gangavaram V. M. Sharma

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