3- Hydroxythiophene, reaction with benzaldehyde

The hydroxythiophenes which exist predominantly as the thiolen-2-ones also show reactions characteristic of the enol form. They can be methylated at the oxygen with dimethyl sulfate of diazomethane and they can also be acylated. - - They also react as thio-lene-2-ones showing a reactive methylene group which can be condensed with benzaldehyde. The danger of using chemical reactivity data for drawing conclusion as to the physical state of these tautomerizable systems has been pointed out. ... 

The following exemplify reactions of the aldol type. 3-Hydroxythiophene with benzaldehyde forms (269). Anions derived from oxindole (270 Z = NH) and indoxyl (271) react with isatin (272) to give isoindigo (273) and indirubin (274). 

---

See also in sourсe #XX -- [ ]

---