Self-assembly of an organocatalyst for the enantioselective synthesis of Michael adducts and alpha-aminoxy alcohols in a nonpolar medium

Demir, Ayhan Sıtkı
A proline-thiourea host-guest complex is described as a self-assembled organocatalyst for the enantioselective Michael addition of aldehydes to nitroolefins and for the asymmetric alpha-aminoxylation of both aldehydes and ketones. The Michael adducts were obtained in good yields of up to 80%, high diastereo-selectivities of up to 5:95, and high enantiomeric excesses of up to 98%. The optically active aminoxy alcohols were synthesized in 60-85% yields with 94-99% enantiomeric excesses after reduction of the alpha-oxidation products using NaBH4.


Self-assembly of organocatalysts for the enantioselective Michael addition of aldehydes to nitroalkenes
Demir, Ayhan Sıtkı; Eymur, Serkan (2010-01-29)
A proline-thiourea self-assembled organocatalyst is described as a good catalyst for the enantioselective nitro-Michael addition of aldehydes to nitroalkenes The reaction is efficient with 5% of the thiourea, to give moderate to good enantioselectivity (up to 76% ee) High syn-selectivity was obtained with both branched and unbranched aliphatic aldehydes This is the first example of self-assembly of organocatalysts with an achiral additive in a Michael addition wherein aldehydes are utilized as donors. (c) 2...
Application of the Ugi reaction with multiple amino acid-derived components: synthesis and conformational evaluation of piperazine-based minimalist peptidomimetics.
Stucchi, Mattia; Cairati, Silvia; Atalay, Rengül; Christodoulou, Michael S.; Grazioso, Giovanni; Pescitelli, Gennaro; Silvani, Alessandra; Kahraman, Deniz Cansen; Lesma, Giordano (2015-05-07)
The concurrent employment of alpha-amino acid-derived chiral components such as aldehydes and alpha-iso-cyanoacetates, in a sequential Ugi reaction/cyclization two-step strategy, opens the door to the synthesis of three structurally distinct piperazine-based scaffolds, characterized by the presence of L-Ala and/or L-Phe-derived side chains and bearing appropriate functionalities to be easily applied in peptide chemistry. By means of computational studies, these scaffolds have been demonstrated to act as min...
Synthesis of Bishomoinositols and an Entry for Construction of a Substituted 3-Oxabicyclo[3.3.1]nonane Skeleton
BARAN, ARİF; Bekarlar, Merve; Aydin, Gokay; NEBİOĞLU, MEHMET; ŞAHİN, Ertan; Balcı, Metin (2012-02-03)
1,3,3a,7a-Tetrahydro-2-benzofuran was used as key compound for the synthesis of various bishomoinositol derivatives. The diene was subjected to an epoxidation reaction for further functionalization of the diene unit. The bisepoxide obtained was submitted to a ring-opening reaction with acid in the presence of water. Various bishomoinositols were synthesized. However, when the reaction was carried out in the presence of acetic anhydride, a substituted 3-oxabicyclo[3.3.1]nonane skeleton was formed. The mechan...
Application of L-prolinamides as highly efficient organocatalysts for the asymmetric Michael addition of unmodified aldehydes to nitroalkenes
Naziroglu, Hayriye Nevin; DURMAZ, MUSTAFA; Bozkurt, Selahattin; Demir, Ayhan Sıtkı; SIRIT, ABDULKADİR (2012-01-31)
The asymmetric Michael addition of aldehydes to nitroolefins was investigated using a combination of L-prolinamide derivatives and various acidic additives. (S)-1,1'-Bi-2-naphthol was found to be the most effective co-catalyst and afforded the nitroaldehyde products with excellent yields (up to 95%), enantiomeric excesses (up to 99%) and diastereoselectivity ratios (up to 99:1).
Coupling of ferrocenyl chromium carbene complex with cyclobutenediones
Zora, Metin; Bekir Peynircioglu, N. (Elsevier BV, 2002-08-15)
The coupling of ferrocenyl chromium carbene complex with cyclobutenediones leads to ferrocenyl-substituted 5-alkylidenefuranones and 4-cyclopentene-1,3-diones, methyl ferrocenoate and acetylferrocene in varying amounts. The scope and limitations of these processes are investigated. In comparison with the phenyl analog, ferrocenyl chromium carbene complex has been found to be less reactive. This is also supported by PM3 calculations. The coupling of ferrocenyl chromium carbene complex with cyclobutenediones...
Citation Formats
A. S. Demir and S. BAŞÇEKEN, “Self-assembly of an organocatalyst for the enantioselective synthesis of Michael adducts and alpha-aminoxy alcohols in a nonpolar medium,” TETRAHEDRON-ASYMMETRY, pp. 1218–1224, 2013, Accessed: 00, 2020. [Online]. Available: