Lithiated (E)-N-isopropyl-5-tosyl-4-pentenamide: Synthetic applications as new δ-acyldienyl anion equivalent

Article abstract of DOI:10.1016/S0040-4020(98)00658-9

The vinyl sulfone (E)-N-isopropyl-5-tosyl-4-pentenamide (14), prepared from 4-pentenoic acid by stereoselective iodosulfonylation-dehydroiodination and further amidation, reacts with two equiv of n-butyllithium at -78°C to give presumably a dilithiated lactam 25. After reaction with aldehydes and propylene oxide or alkyl halides (2E,4E)-6-hydroxy and 7-hydroxy-2,4- hexadienamides 15 and 21 or alkylated dienamides 18 and 20 are stereoselectively obtained, respectively. In the case of carboxylic acid chlorides or cyclohexyl isocyanate, dilithiated lactam 25 undergoes acylation to afford the corresponding lactam derivatives 22. The 6-hydroxy-2,4- dienamide 15f has been transformed into the 6-oxo-2,4-dienamide 41 by oxidation or into the (2E,4E,6E)-trienamide 42 by bromination reactions.