The reaction of heteroaryl iodides with i-PrMgBr (ca. 1.0 equiv) in THF provides the corresponding magnesiated heterocycles. Functional groups such as an ester, cyano, or chloride functions are tolerated in these new Grignard reagents if the exchange can be performed below -20 degrees C. This is the case for all heterocycles bearing electron-withdrawing groups or chelating functions facilitating the iodine-magnesium exchange. In many cases, the exchange can be extended to heteroaryl bromides, and a case of a chlorine-magnesium exchange is described with tetrachlorothiophene. This new preparation of functionalized heteroarylmagnesium compounds provides after reaction with various electrophiles a new entry to a broad range of polyfunctional pyridines, imidazoles, furanes, thiophenes, pyrroles, antipyrines, and uracil derivatives. The application of the halogen-magnesium exchange in the solid phase allows the performance of solid-phase synthesis, with potential applications for combinatorial chemistry.

A general and efficient copper(I)-catalyzed cross-coupling and heterocyclization reaction of terminal alkynes and b-iodo-a,b-unsaturated acid derivatives has been developed under very mild conditions. This method provides easy access from good to excellent yields of a variety of 5-ylidenebutenolides and 3-substituted isocoumarins with excellent regioand stereoselectivity. This procedure does not require the use of any expensive supplementary additives, and is palladium-free.

Palladium-catalyzed stereoselective annulation of a functional vinylstannane by acyl chlorides gives the corresponding alpha-pyran-2-ones in good yields. This annulation most probably proceeds through a Stille reaction/cyclization sequence.

A general route to alpha-pyrones and 3-substituted isocoumarins from (Z)-iodovinylic acids 1a-f or 2-iodobenzoic acids 4a-c is described, including compounds bearing a substituent on the aromatic ring. Treatment of (Z)-beta-iodovinylic acids 1a-f or 2-iodobenzoic acids 4a-c with various allenyltributyltin reagents in the presence of palladium acetate, triphenylphosphine, and tetrabutylammonium bromide in dimethylformamide provided good yields of the corresponding alpha-pyrones 3a-k or 3-substituted isocoumarins 5a-g via tandem Stille reaction and 6-endo-dig oxacyclization.