3-Iodo-4-chalcogen-2H-benzopyran as a convenient precursor for the sonogashira cross-coupling: synthesis of 3-alkynyl-4-chalcogen-2H-benzopyrans

3-Iodo-4-chalcogen-2H-benzopyran derivatives underwent a direct Sonogashira cross-coupling reaction with several terminal alkynes in the presence of a catalytic amount of Pd(PPh3)2Cl2 with CuI as a co-catalyst, using Et3N as base and solvent. This cross-coupling reaction proceeded cleanly under mild conditions and was performed with propargylic alcohols, propargylic ethers, as well as alkyl and aryl alkynes, furnishing the correspondent 3-alkynyl-4-chalcogen-2H-benzopyrans in good yields.

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