Herein we report a palladium-catalyzed [2+2+1] annulation among 3-iodochromones, bridged olefins, and cyclopropenone, giving a variety of chromone fused cyclopentanones that are of interest in medicinal chemistry. This protocol involves...

Main observation and conclusion 1,3‐Butadiene plays a key role in modern synthetic chemistry and biochemistry because it is a key intermediate in the synthesis of many drugs. A new and effective method for the synthesis of 4‐trifluoromethylated 1,3‐butadiene through the fluorinated Heck reaction catalyzed by Pd(0) is described. Without additives, 1‐chloro‐3,3,3‐trifluoropropene (an inexpensive CF3 structural unit that is harmless to ozone) reacts with enamide to synthesize 4‐trifluoromethylated 1,3‐butadienes with good yield, high regioselectivity and chemical selectivity, and strong tolerance of substrate functional groups such as alkynes, aldehyde, and ester groups.

By using 2-(fluorosulfonyl)difluoroacetic acid as sulfur ­reagent, bisindole sulfanes were highly efficient synthesized under transition-metal-free conditions. Results indicate that this proceeded not at the relatively acidic C-2 position but rather selectively at the nucleo­philic C-3 position to give the desired compounds with excellent regio­selectivities and good yields.

1,3-Butadienes play a key role in modern synthetic chemistry and biochemistry because they are well-known precursors for the synthesis of retinoids.