Thiophene-Based Quinomethane Analogs

The chemistry of the stable thiophene-based quinomethane analogs, namely, 3-alkylidenethiophen-2-ones, 2-alkylidenethiophen-3-ones, and 5-alkylidenethiophen-2-ones, is reviewed up to late 2016 with 200 literature references. For each of the three ring systems, the properties, reactivity, synthesis, and applications are systematically covered.