Benign and High-Yielding, Large-Scale Synthesis of Diphenylphosphinodithioic Acid and Related Compounds

Diphenylphosphinodithioic acid ( 6b ) and its triethyl ammonium salt ( 6a ) were prepared by two new synthetic pathways, each employing cheap and readily available starting materials. These facile one-pot reactions were conducted on a kilogram scale and produced the desired products in high yield and quality, thereby surpassing all previously known routes. The synthesis of triethyl ammonium salts of 6 H -dibenzo[ c, e ][1,2]oxaphosphinine-6-thiolate 6-sulfide ( 3a ) was also further improved.