α-Nitro-α,β-Unsaturated Ketones: An Electrophilic Acyl Transfer Reagent in Catalytic Asymmetric Friedel–Crafts and Michael Reactions

Abstract

Herein, we introduce α-nitro-α,β-unsaturated ketones as efficient electrophilic acyl transfer reagents, and they were employed in Friedel–Crafts as well as in Michael reactions. The desired acyl transfer products of these reactions were obtained in high yields with high to excellent enantioselectivities with t-leucine-derived squaramide catalyst under mild reaction conditions. Few applications including a synthesis of the isoxazoline motif have been demonstrated.

Unravelling the Development of Non-Covalent Organocatalysis in India

“…Friedel-Crafts acyl transfer reactions using -nitro-,-unsaturated ketones 94 Scheme 42 Enantioselective synthesis of pyranopyrazoles 90…”

“…Scheme 45 An organotandem Michael/acyl transfer reaction of -nitroketones with /-hydroxyenones 93 Pan's group has also reported the first example of -nitro-,-unsaturated ketones 136 as potential electrophilic acyl transfer reagents in reactions with 137 and 139 via conjugate 1,4-additions along with enantioselective Friedel-Crafts reactions with concomitant acyl transfer (Scheme 46). 94 These reactions are catalysed by t-leucinederived squaramide catalyst 3J and give the desired acyl transfer products 138 and 140 in high yields and enantioselectivities under mild conditions. The products having acyl and nitro groups are of pharmaceutical significance.…”

α‐Substituted Chalcones: A Key Review

“…After reduction of the prepared α‐nitrochalcone with LiAlH 4 followed by acetylation, P 2 O 5 or POCl 3 ‐cyclization afforded 2‐oxazoline (reaction 3, Figure 31). α‐Nitrochalcones have been used as electrophilic acyl transfer reagents [135] . These chalcones were also employed in Friedel‐Craft's acylation using an organocatalyst (reaction 4, Figure 31).…”

Acyl transfer-enabled catalytic asymmetric Michael addition of α-hydroxy-1-indanones to nitroolefins

“…Very recently, Yi et al have established an elegant iridium-catalyzed asymmetric cascade allylation/acyl transfer reaction for the synthesis of enantiomerically enriched 3-hydroxymethyl pentenal units [17] . Besides, using acyl transfer, Zhou, Yang et al prepared the medium-sized-ring lactams from cyclobutanone β-ketoamides [18][19][20][21] . Despite these achievements via nucleophile activation, acyl transfer via electrophile activation remains far less developed [Scheme 1C].…”