Volhard–Erdmann cyclization

The Volhard–Erdmann cyclization is an organic synthesis of alkyl and aryl thiophenes by cyclization of disodium succinate or other 1,4-difunctional compounds (γ-oxo acids, 1,4-diketones, chloroacetyl-substituted esters) with phosphorus heptasulfide. The reaction is named after Jacob Volhard and Hugo Erdmann.{{ OrgSynth | author = Feldkamp, R. F.; Tullar, B. F. | title = 3-Methylthiophene | year = 1954 | volume = 34 | pages = 73 | collvol = 4 | collvolpages = 671 | prep = cv4p0671 }}

An example is the synthesis of 3-methylthiophene starting from itaconic acid:{{ cite journal | title = Synthetische Darstellung von Thiophen |author1=Volhard, J. |author2=Erdmann, H. | volume = 18 | issue = 1 | pages = 454–455 | journal = Chemische Berichte | year = 1885 | doi = 10.1002/cber.18850180199 |url=https://zenodo.org/record/1425395 }}

:Volhard-Erdmann cyclization