A dramatic synergistic effect of a flexible achiral linker on a rigid chiral cis-1,2-diamine bifunctional organocatalyst

Abstract

The combination of a "rigid" chiral bicyclic cis-1,2-diamine skeleton with steric bulkiness and a "flexible" achiral linker was newly designed as a bifunctional organocatalyst framework and it showed excellent catalytic activity of up to 0.05 mol%, accompanied by the reversal of enantioselection depending on the position of the linker, in an amine-thiourea organocatalyzed asymmetric Michael reaction.

Stereodivergent Catalysis

“…Chiral bicyclic cis -1,2-diamines 352 bearing a thiurea unit catalyzed the enantiodivergent CA of acetylacetone to nitroalkenes . For example, in the case of the addition to β-nitrostyrene organocatalyzed by 352a the adduct ( R )- 353 was obtained in 89% ee, whereas 352b gave the enantiomer ( S )- 353 in 95% ee (Scheme ).…”

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis ofmeso-cyclic anhydrides

“…Major families originating from natural products include cinchona alkaloids [8–17] and proteinogenic α-amino acids such as proline [18–20] and valine [21] etc. [22–29], while fully synthetic catalysts are rare, only involving Brønsted acid/base catalysts [30], cyclohexanediamine catalysts [31–32], and diphenylethylenediamine catalysts [33–34]. Significant progress in our laboratory has been made in the development of chiral bifunctional urea 1 [35], thiourea 2 and 3 [36–37], sulfonamide 4 [38–40] and squaramide 5 [38–40] catalysts derived from chloramphenicol base (Fig.…”