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Here we describe the first attempts to scale up five addition reactions between (SS)-N-tert-butanesulfinyl-(3,3,3)-trifluoroacetaldimine 6 with C-nucleophiles derived from ketones (two examples), glycine Schiff base and heterocycles (two examples). In all cases studied, the observed stereochemical outcome of the scaled up (5.0-25.0 mmol) reactions was lower as compared with the original 0.5 mmol scale. However, the observed worsening of yields and diastereoselectivity was not identical and depended on the reaction conditions and reaction mechanisms. In general, scaling up of the reactions conducted at ambient temperatures presented no problems while the low-temperature (-78 °C) processes would require special equipment to provide strict maintenance of the reaction temperature to obtain the desirable outcome. Importantly, using procedures described here, series of biologically relevant compounds containing 2,2,2-trifluoro-1-(amino)ethyl [CF3CH(NH2)-] pharmacophore unit can be prepared in enantiomerically pure form on up to 5 g scale, allowing their systematic biological studies. [ABSTRACT FROM AUTHOR]

A combination of benzyl carbamate and N-chlorosuccinimide was developed as a new system for aminohalogenation of bnitrostyrenes catalyzed by potassium carbonate in dichloromethane at room temperature. The reaction tolerates a wide range of substituents on the b-nitrostyrene, and proceeds smoothly in good-toexcellent chemical yields (77-99%). The new system shows a high efficiency and it markedly shortens the reaction time for aminochlorination. N,N-Dichlorobenzyl carbamate was also found to be a highly efficient source of both nitrogen and chlorine for the aminohalogenation reaction. [ABSTRACT FROM AUTHOR]

An efficient one-pot system has been developed for the synthesis of cyano aziridine by using α, β-unsaturated nitriles as the alkene substrates and N,N-dichloro- p-toluenesulfonamide (4-TsNCl2) as the nitrogen source. A good scope of alkene substrates was achieved for this reaction. The one-pot reaction, via aminohalogenation and intramolecular SN2 substitution, was very convenient to carry out at room temperature without the protection of inert gases. Modest to good yields and excellent have been obtained. This method provides an easy route to the cyano aziridine. The structure of the resulting products has been unambiguously confirmed by X-ray structural analysis. [ABSTRACT FROM AUTHOR]

An efficient direct aldol reaction has been developed for the synthesis of chiral β-hydroxy ketone using a combination of C-symmetric chiral prolinamides based on o-phenylenediamine and zinc triflate as catalyst. The reaction was convenient to carry out in aqueous media with up to 98% chemical yields and up to 94% ee values. The current strategy can be regarded as the analogue of aldolase type II, which suggests a new pathway for the designing of new organocatalysts. [ABSTRACT FROM AUTHOR]

Asymmetric detrifluoroacetylative Mannich reactions between a-fluorinated arylsulfonyl gem-diols and fluoroalkyl imines have been developed under operationally convenient conditions. Varieties of a-fluorinated arylsulfonyl gem-diols and fluoroalkyl imines are well tolerated with the corresponding a-difluorinated ß-amino sulfone products generated in moderate to excellent yields as well as high diastereoselectivity. The reaction can be reproduced on gram-scale with uncompromised yield and stereochemical outcome. The synthetic value of the products is demonstrated by two transformations by means of desulfonylation and removal of the sulfinyl protecting-group. [ABSTRACT FROM AUTHOR]