Thiourea dioxide, an efficient reagent to reduce aryl-N-nitrosamines to the corresponding hydrazines
Various reagents, such as lithium aluminum hydride, stannous chloride, zinc, hydrogen in presence of palladium on carbon or Raney nickel have been used for partial reduction of aryl-N-nitrosamines to the corresponding hydrazines. [1] Thiourea dioxide (TDO, 100 euros / 1 kg) widely known as a “green industrial reductant” is an excellent reagent to carry out this transformation as presented in the Scheme below. [2]
A mechanism for the reduction of N-nitrosamines with thiourea dioxide involving the in situ formation of sulfoxylic acid (S(OH)2) as reducing agent is proposed.
[1] C. J. Borths, M. Burns, T. Curran, N. D. Ide, Org. Process Res. Dev. 2021, 25, 1788-1801.
[2] P. Chaudhary, S. Gupta, P. Sureshbabu, S. Sabiah, J. Kandasamy, Green Chem. 2016, 18, 6215-6221.
