Reaction of vinyl triflates of α-keto esters and imides with secondary amines: synthesis of α,β-diamino carboxylic acid derivatives through aziridinium ions

SF5-Enolates in Ti(IV)-Mediated Aldol Reactions

The F···Ti bonding in the transition structures determines high trans- and syn-diastereoselectivities for aldol reactions of SF5-acetates with aldehydes in the presence of TiCl4 in the non-nucleophilic solvent CH2Cl2. Such bonding is canceled in nucleophilic solvents where opposite cis-stereochemistry is observed. The potential of thus obtained stereoisomeric SF5-aryl acrylates as dipolarophiles in the preparation of SF5-containing heterocycles is demonstrated.

Memory of chirality (MOC) concept in imino-aldol reaction: enantioselective synthesis of α,β-diamino esters and aziridines

A simple strategy for the synthesis of chiral α,β-diamino- and α-amino,β-hydroxy ester derivatives in high yields with moderate to high ee has been developed via asymmetric imino-aldol and aldol reactions, respectively, starting from protected aminoesters employing memory of chirality concept for chiral induction. This strategy has been extended for the enantioselective synthesis of aziridines (ee up to 92%). The absolute configuration of the imino-aldol adducts has been determined. The stereochemical outcome of the products has been explained by a suitable mechanism and supported by computational studies.

Rearrangement of beta-amino alcohols via aziridiniums: a review

This tutorial review focuses on the rearrangement of beta-amino alcohols via aziridinium intermediates. It covers the literature from 1947 to January 2009 (55 references). The rearrangement of beta-amino alcohols can be performed by activation of the hydroxy group followed by the addition of nucleophiles (Nu). In most examples, an aziridinium intermediate is involved in the rearrangement. The ratio of amines resulting from the attack of nucleophiles at either the C-1 or C-2 position of the aziridinium intermediate, depends on the nature of the nucleophiles and the R(2) substituent. In some cases, solvent as well as temperature can influence the ratio of amines.

Novel Synthesis of 3,4-Diaminobutanenitriles and 4-Amino-2-butenenitriles from 2-(Cyanomethyl)aziridines through Intermediate Aziridinium Salts: An Experimental and Theoretical Approach

1-Arylmethyl-2-(cyanomethyl)aziridines were transformed into 4-(N,N-bis(arylmethyl)amino)-3-(pyrrolidin-1-yl)butanenitriles and 4-(N,N-bis(arylmethyl)amino)-2-butenenitriles via 4-(N,N-bis(arylmethyl)amino)-3-bromobutanenitriles in high yields and purity. The key steps involve the unprecedented regiospecific ring opening of intermediate 2-(cyanomethyl)aziridinium salts by bromide and pyrrolidine in acetonitrile, exclusively at the substituted aziridine carbon atom. The results were rationalized on the basis of ab initio calculations.