2-Chlorotetrafluoroethanesulfinamide induced asymmetric vinylogous Mannich reaction

The generality of (S)-2-chlorotetrafluoroethanesulfinamide (CTFSA) induced asymmetric vinylogous Mannich (AVM) addition reaction has been investigated. The reaction of aldimines derived from (S)-CTFSA with 2-(tert-butyldimethylsilyloxy) furan (TBSOF) took place regioselectively at the γ-site at room temperature in DMSO under air atmosphere to give the desired addition products in syn-configuration with high diastereoselectivities (up to 98:2 dr). However, anti-configuration product as major isomer was obtained in the presence of tetra-butyl ammonium fluoride (TBAF) at −78 °C. Facile removal of the auxiliary group without epimerization demonstrated their synthetic potential for piperidone derivatives.

(S)-2-Chlorotetrafluoroethanesulfinamide induced 2-(tert-butyldimethylsilyloxy) furan-based asymmetric vinylogous Mannich reaction was studied. The reaction gave the corresponding adduct in syn-configuration in good yield with high stereoselectivity in DMSO. However, anti-isomer was obtained as the major product in the presence of (TBAF)(tBuOH)2.6.