Metal-Free Tandem Oxidative Aryl Migration and C–C Bond Cleavage: Synthesis of α-Ketoamides and Esters from Acrylic Derivatives

Abstract

A novel tandem metal-free oxidative aryl migration/C-C bond-cleavage reaction, mediated by hypervalent iodine reagent, has been discovered. The presented transformation provided straightforward access to important α-ketoamide and α-ketoester derivatives from readily available acrylic derivatives via a concerted process of 1,2-aryl shift concomitant with C-C bond cleavage.

Enantioselective Oxidative Rearrangements with Chiral Hypervalent Iodine Reagents

“…[16] Ring-contrac-Scheme1.Asymmetric strategies to a-arylated ketones. tion and ring-expansion reactions of cyclic alkenesh ave been demonstrated using 1, [17] and 1,2-aryl shifts of acrylamide derivatives, [18] arylalkenes [19] and 1,1-diphenylalkenes [20] have been performed in ar acemic fashion using 1 or its derivatives. Althoughchiral hypervalent iodine reagents in stereoselective reactions have received much attention, [21] their use in stereoselective rearrangements are still scarce.…”

Recent discoveries on the structure of iodine(iii) reagents and their use in cross-nucleophile coupling

“… 75 ‡ ‡ If the conditions are varied, the acetal product ( 110 ) may be further oxidized to yield the α-aryl–α-keto carbonyl compound. 163 …”

Rearrangements Induced by Hypervalent Iodine

“…This transformation appears to be compatible with several aryl groups and may also be performed in the presence of different N-aryl substituents. The same group has demonstrated that treatment with (diacetoxyiodo)benzene in the presence of sulfuric acid transforms acrylic amides 44 into α-ketoamides 51 as shown in Scheme 15 [12]. The process is an example of a tandem aryl migration/C-C A second attack of the amide (via the iminium ion) on the hypervalent iodine(III) with departure of a hydrogen atom generates 48, which is hydrolyzed to 49.…”