A practical and eco-friendly synthesis of stereocontrolled alkylaminomethylidene derivatives of 2-thiohydantoins by dimethylamine substitution

3-Alkyl-5-dimethyaminomethylidene-2-thioxo-imidazolidin-4-ones 3(a–c) available in two steps from methyl glycinate hydrochloride, represent a useful synthetic tool for efficient and mild solventless preparations of new alkylaminomethylidene derivatives of 2-thiohydantoins 8(a–e), 10(a–c) and 12(a–d) by stereocontrolled transamination reactions under microwave irradiations. The 1H, 13C NMR spectrum and the (5Z)-conformation of some representatives products are also discussed.