The 3-bromo-2-t-butylsulfonyl-1-propene 3 was prepared in two steps from allyl-t- butylthioether in 70% overall yield. This reagent reacts selectively with a broad range of nucleophiles (amine, thiolate, lithium ester-and keto-enolates, magnesium, zinc and lithium organomatallics) to furnish the unsaturated sulfones of type 4 in typical yields of 80–90%. The sulfone 3 reacts also in the presence of zinc with various electrophiles (aldehydes, ...