Catalytic Activity of epi-Quinine-Derived 3,5-Bis(trifluoromethyl)benzamide in Asymmetric Nitro-Michael Reaction of Furanones

Abstract

High catalytic activity of novel epi-quinine-derived 3,5-bis(CF3)benzamide in the asymmetric nitro-Michael reaction is described. With 0.1-5 mol % loadings of this catalyst, the addition of 5-substituted 2(3-H)-furanones to a wide range of nitroalkenes involving challenging substrates, β-alkylnitroalkenes, smoothly proceeded, giving the Michael adducts in high yields (>90%) with excellent diastereo- and enantioselectivity (>98:2 dr, syn major; 88-98% ee). DFT calculation was carried out to account for the high catalytic activity.

Angelica Lactones: From Biomass‐Derived Platform Chemicals to Value‐Added Products

“…Later on, Hatanaka and co-workers developed as imilar organocatalytic Michael addition of a-AL to nitroalkenes (Scheme41). [70] In this approach, the authors disclose the use of epi-quinine-derived 3,5-bis(CF 3 )benzamide bifunctional catalyst O to promotet he conjugate addition, even with poorly reactive b-alkylnitroalkenes. Concerning the reaction scope, several b-arylnitroolefins with electron-donatinga nd electron-Scheme38.…”

“…In this case, the umpolung vinylogousa ddition of this core to allenoates 55 is reported for the first time by using ac ombinationo fa na chiral phosphine (PPh 3 )a nd chiral squaramide H-bond-donating catalyst P (Scheme 43). [73] Here, the initial addition of PPh 3 [70] Scheme42. Cascade Michael-aldol reaction of b-AL to aldehydes.…”

Switchable Diastereoselectivity in the Fluoride-Promoted Vinylogous Mukaiyama–Michael Reaction of 2-[(Trimethylsilyl)oxy]furan Catalyzed by Crown Ethers

“…Surprisingly, in the nonpolar toluene solvent (ε 2.38), the diastereoselectivity was reversed, with a marked preference for the syn -product 4a (7:93 anti / syn , entry 10). To the best of our knowledge, such a striking solvent-dependent inversion of diastereoselectivity is unprecedented in the synthesis of butenolides by VMMR . This finding appears to be of great synthetic interest in that a single catalytic system can lead to both the anti - and syn -diastereomers just by choosing the appropriate solvent.…”

Cinchona Derivatives as Bifunctional H‐bonding Organocatalysts in Asymmetric Vinylogous Conjugate Addition Reactions

“…In 2015, Hatanaka and co‐workers studied the γ‐reactivity of deconjugated butenolides in VCA reactions to nitroolefins under epi ‐quinine‐based 3,5‐bis(trifluoromethyl)benzamide C6 catalysis (Scheme 4). [15] Several nitroalkenes 4 with aryl or even alkyl β‐substituents were allowed to react with γ‐substituted butenolide 8 under the optimized conditions, and the corresponding syn ‐adducts 10 were isolated in high yields with high optical purity. Bifunctional system C6 has a H‐bond donor −NH group at C‐9 carbon.…”