Catalyst‐Dependent Rate‐Determining Steps in Regiodivergent Vinylogous Aza‐Morita‐Baylis‐Hillman Reactions with <i>N</i> ‐Ts Imines.

3-Bromooxindoles as nucleophiles in asymmetric organocatalytic Mannich reactions with N-Ts-imines.

A direct asymmetric Mannich reaction of N-unprotected 3-bromooxindoles with N-Ts-imines catalyzed by bifunctional thiourea derived from 2-substituted cinchona alkaloid was developed. Products with vicinal chiral tertiary and brominated quaternary stereogenic centers were achieved in excellent diastereo- and enantioselectivity (up to 99 : 1 dr, 99% ee).

Reactions of dimethoxycarbene with N-tosylated imines

The reactions of dimethoxycarbene (DMC; 2), which was generated in situ by thermal decomposition of 2,5-dihydro-2,2-dimethoxy-5,5-dimethyl-1,3,4-oxadiazole (1), with N-tosylated imines of xanthone and 2,3 : 6,7 dibenzosuberenone, 3a and 3d, respectively, led to different adducts with rearranged skeletons. In the case of 3a, the 1 :1 adduct 5 as well as the 2 : 1 adduct 6 were obtained (Scheme 2...

Disulfonimide-catalyzed asymmetric vinylogous and bisvinylogous Mukaiyama aldol reactions.

The term vinylogy, which describes a unique property of p systems where the electron density and reactivity is amplified along conjugated bonds, was proposed 75 years ago by Fuson. The principle becomes particularly relevant in the context of the aldol reaction: While metal dienolates often furnish mixtures of aand g-addition products, the corresponding dienolsilanes react with high selectivity...

Steps in the reactions of chymotrypsin with tyrosine derivatives.

Organocatalytic asymmetric direct vinylogous aldol reactions of γ-crotonolactone with aromatic aldehydes.

The direct aldol reaction of γ-crotonolactone and various aromatic aldehydes is catalyzed by bifunctional aminothiourea and aminosquaramide organocatalysts to provide diastereomerically and enantiomerically enriched 5-substituted 2(5H) furanones (γ-butenolides). The reaction is a simple alternative to the classical vinylogous aldol reaction of silyloxy furans.