Chlorotrimethylsilane → 5-Iodo-2-trimethylsilyloxypyrimidine

Participants

Reaction Steps

A suspension of 15.06 g (67.83 mmol) of 5-iodo-2(1H)-pyrimidinone was refluxed in 40 ml of hexamethyldisilazane and 2 ml of chlorotrimethylsilane for 1 hour. The excess reagent was removed in vacuo to yield a yellow oil 5-iodo-2-trimethylsilyloxypyrimidine, which was dissolved with 30 ml of dry degassed triethylamine. To this solution was added 11.5 ml (81.37 mmol) of trimethylsilylacetylene, 0.32 g (2.5 mol %) of CuI and 0.48 g (1 mol %) of (φ3P)2PdCl2. The reaction mixture was stirred under nitrogen, at room temperature, for 3 days and diluted with 100 ml of dry THF. The mixture was filtered under dry nitrogen; the precipitate washed several times with dry THF and the filtrate was concentrated to a residue. The latter was treated with methanol to give a white crystalline, chromatographically homogeneous material 5-(2-Trimethylsilyl)ethynyl-2(1H)-pyrimidinone (9.99 g, 76.6%). Analytically pure material could be obtained by recrystallization from methanol; mp 203°-206° C.

Provenance & Evidence