Search

The investigation of the reactivity of an α-amido sulfone derived from 2-formyl benzoate under organocatalytic conditions in the presence of acetylacetone allowed the synthesis of a new heterocyclic hybrid isoindolinone-pyrazole with high enantiomeric excess. Dibenzylamine was also used as a nucleophile to afford an isoindolinone with aminal substituent in 3-position in suitable selectivity. The use of Takemoto's bifunctional organocatalyst not only led to observed enantioselectivity but was also important in accomplishing the cyclization step in both cases. Notably, this catalytic system proved to be particularly effective in comparison to widely used phase transfer catalysts. [ABSTRACT FROM AUTHOR]

We herein report a protocol for the asymmetric aldol‐initiated cascade addition of isoxazolidin‐5‐ones to ortho‐cyanobenzaldehydes by using Takemoto's bifunctional organocatalyst. This approach allows for the synthesis of various novel β2,2‐amino acid‐phthalide conjugates with good enantio‐ and diastereoselectivities in reasonable yields and the further ring‐opening of these compounds to acyclic carboxylic acid derivatives was demonstrated too. [ABSTRACT FROM AUTHOR]

Herein, we report the application of an efficient and practical K2CO3 promoted cascade reaction of 2-acetylbenzonitrile in the synthesis of novel 3-methylated analogs of Pazinaclone and PD172938, belonging to isoindolinones heterocyclic class bearing a tetrasubstituted stereocenter. Organocatalytic asymmetric synthesis of the key intermediate and its transformation into highly enantioenriched 3-methylated analog of (S)-PD172938 was also developed. These achievements can be of particular interest also for medicinal chemistry, since the methyl group is a very useful structural modification in the rational design of new and more effective bioactive compounds. [ABSTRACT FROM AUTHOR]

A novel Brønsted acid promoted condensation reaction between a primary aniline and 2-hydroxycyclobutanone provides access to diverse tryptamine derivatives in moderate to good yields. The proposed mechanism involves an α-iminol rearrangement, ring expansion, ring closure, and a depart-and-return rearrangement process. [ABSTRACT FROM AUTHOR]

We have developed one‐step protocols for the preparation of a large selection of α‐aminocyclopropyl ketones or benzo[d]imidazoles, by reacting 2‐substituted‐2‐hydroxycyclobutanones with aryl amines or o‐phenylenediamines, respectively. In most case the reactions proceed at room temperature and are catalyst‐free. The formation of benzo[d]imidazoles is rationalized in terms of an unusual ring‐closure/ring‐fission process followed by aromatization. [ABSTRACT FROM AUTHOR]

A new Brønsted acid catalysed solvent‐free cascade reaction consisting of a ring closure‐ring fission process between α‐arylaminocyclobutanones and alcohols has been established, providing highly functionalised 3‐(2‐alkoxyethyl)indoles in good to excellent yields. [ABSTRACT FROM AUTHOR]