Effective synthesis of ortho-substituted trithiophenol amines by Miyazaki-Newman-Kwart rearrangement

An efficient synthesis of ortho-substituted trithiophenol amines from commercially available salicaldehydes by Miyazaki-Newman-Kwart rearrangement/threefold reductive amination is reported. The rearrangement has been carried out on salicaldehyde-O-thiocarbamates using microwave induced heating, which furnishes a series of thiosalicaldehyde-S-carbamates in high yield. The thiocarbamate has three roles: it enables effective S-O rearrangement, acts as a protecting group during the threefold reductive amination and can be easily removed under reductive conditions. The three-step synthesis has an overall yield ranging from 30-35%, and it enables access to a series of increasingly important C(3v) symmetric ligands in a structurally systematic way