Efficient Asymmetric α-Oxyamination of Aldehydes by Resin-Supported Peptide Catalyst in Aqueous Media

Abstract

The resin-supported peptide catalyst having the terminal five-residue Pro-d-Pro-Aib-Trp-Trp combined with polyleucine successfully catalyzed the asymmetric alpha-oxyamination of aldehydes in aqueous media. The secondary structure and the chirality sense of the hydrophobic polyleucine chain significantly affected both reactivity and enantioselectivity.

Asymmetric one-pot sequential Friedel–Crafts-type alkylation and α-oxyamination catalyzed by a peptide and an enzyme

“…2) for several organic reactions in aqueous media [30–37]. Since these catalysts can be applicable for the FCAA reaction toward α,β-unsaturated aldehydes through iminium intermediates [32,37], and an asymmetric α-oxyamination of aldehydes via enamines [33], they are expected to be suitable for a one-pot sequential reaction to make the chiral indoles mentioned above. Herein, we report on an enantioselective synthesis of oxygenated indole compounds through a one-pot sequential FCAA/α-oxyamination catalyzed by the resin-supported peptide.…”

“…The desired two-step reaction product 4 was obtained with syn/anti ratio of 75:25, and the ee value of the syn diastereomer was 96% (Table 1, entry 1). It is noteworthy that the ee of the major diastereomer was higher than that of each single reaction [33,37]. Such enantio-enrichment is generally caused in consecutive catalytic asymmetric reactions through the formation of diastereomeric pairs [17,41].…”

Asymmetric one-pot reactions using heterogeneous chemical catalysis: recent steps towards sustainable processes

“…171 This oxamination was catalysed by the resinsupported oligopeptide CT19* catalyst using FeCl 2 and NaNO 2 in aqueous media under aerobic conditions. 172 The novel tandem reaction occurred under similar conditions, except that 15 used as reactant in the second step also served as oxidant in the CuIJI)/15 catalysed and 1,1′-bipyridine additive assisted first homogeneous oxidation step of the process. Good yields and high enantioselectivities were reached, determined following an additional reduction of the cascade products 115 to alcohols 116.…”

Pursuing Chemical Efficiency by Using Supported Organocatalysts for Asymmetric Reactions under Aqueous Conditions

“…In addition, iron trichloride (30 mol%) was used as SET reagent in the α−oxyamination of aldehydes, using as catalyst a resin-supported peptide (93, n = 25.4, 20 mol%) in the presence of sodium nitrate. After in situ reduction with NaBH 4 , the α-oxygenated product 91a (R 2 = CH 2 OH) was obtained in good yields and enantioselectivities (73-84%, 87-93% ee), working in a mixture THF:water (1:2) as solvent [167]. The procedure was extended to a one-pot sequential reaction, starting from primary alcohols, using copper(I) chloride under aerobic conditions.…”