Diethyl thioxomalonate

In a related approach, a, /i-unsaturated thioketones, formed in situ by thionation with P4S10 of the corresponding ketones, undergo intramolecular hetero-Diels-Alder reactions263. Diethyl thioxomalonate was formed from diethyl oxomalonate and phosphorus pentasulfide (equation 29) and was trapped as a Diels-Alder adduct264. 

A new method for the preparation of diethyl thioxomalonate, already prepared from Bunte salts340 (Section m.E.5), has been introduced by Abelman351. In this approach, diethyl chloromalonate was reacted with cesium carbonate in the presence of elemental sulfur to yield the thioxoester which underwent a facile [4+2] cycloaddition (equation 74). 

Diethyl thioxomalonate, S=C(COOC2H5)2 (1). This reagent can be generated in situ from the Bunte salt (2) prepared by reaction of diethyl chloromalonate with sodium thiosulfate. 

---

See also in sourсe #XX -- [ ]

---