Stannane, tributyl(1-ethoxyethenyl)- → 1-(3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-one

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Reaction Steps

In accordance with this scheme a 6-bromochroman compound of Formula 2 (see Reaction Scheme 1) is reacted with by tributyl(1-ethoxyvinyl)tin in the presence dichlorobis(triphenylphosphine)palladium(II) under an inert gas (argon) atmosphere in an aprotic neutral solvent, such as tetrahydrofuran (THF), to provide a 6-acetylchroman derivative of Formula 25. The 6-acetylchroman derivative of Formula 25 is then reacted with iodine and silver(I)trifluoromethanesulfonate (AgOTf) to give a 6-acetyl-8-iodochroman derivative of Formula 26. The compound of Formula 26 is reacted with with trimethylsilyl acetylene in triethyl amine under argon atmosphere in the presence of copper(I)iodide and dichlorobis(triphenylphosphine)palladium(II) (Pd(PPh3)2Cl2) to give the 6-acetyl-8-trimethylsilanyl-ethynyl-chroman derivative of Formula 27. The latter reaction is analogous to the conversion of the 8-iodo-substituted chroman compounds of Formula 4 to the 8-trimethylsilanyl-ethynyl-chroman derivatives of Formula 5, as shown in Reaction Scheme 1.

Provenance & Evidence