Sandmeyer diphenylurea isatin synthesis

What is Sandmeyer diphenylurea isatin synthesis?

The Sandmeyer diphenylurea isatin synthesis involves the creation of isatin-2-anil through a series of chemical reactions.

Sandmeyer diphenylurea isatin synthesis - general reaction scheme
Sandmeyer diphenylurea isatin synthesis

First, a symmetrical diphenylthiourea is treated with potassium cyanide (KCN) in an alcohol solution containing lead carbonate (EtOH/PbCO3), resulting in the formation of a cyanoformamidine. This compound is then reduced with ammonium sulfide (NH4)2S and subjected to ring-closure with concentrated sulfuric acid (H2SO4), leading to the formation of isatin-2-anil. Another method to obtain this compound is by performing the ring-closure of the cyanoformamidine with aluminium chloride (AlCl3) in either benzene or carbon disulfide CS2, which proceeds smoothly.

References

  • T. Sandmeyer, Z. Farb. Textile Chem. 2, 129 (1903)
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