Facile synthesis of 5-(alkylidene)thiophen-2(5H)-ones. A new class of antimicrobial agents

5-(Chloromethylene)- and 5-(bromoalkylidene)thiophen-2(5H)-ones are easily prepared from readily available 2-acyl-5-methoxythiophenes in one step by reaction with excess acetyl chloride or acetyl bromide. Other 5-(methylidene)thiophen-2(5H)-ones have been made from 5-(bromomethylene)thiophene-2(5H)-one by treatment with different nucleophiles. Eighteen thiophenones were tested for capacity to reduce biofilm formation by the marine bacterium V. harveyi. All but three compounds reduced biofilm formation markedly. For all effective compounds but one, the relative biofilm reducing capacity was greater than inhibition of bacterial planktonic growth.