The First Tandem Acetalization/5-<i>exo</i>-<i>dig</i> Cyclization of 6-Phenylethynylpyrimidine-5-carbaldehydes: Efficient Synthesis of 5-Alkoxy-(7<i>Z</i>)-7-benzylidene-5<i>,</i>7<i>-</i>dihydrofuro[3,4-<i>d</i>]pyrimidines
The first example of catalyst-free tandem acetalization/5-exo-dig cyclization reactions of 6-phenylethynylpyrimidine-5-carbaldehydes is presented. Efficient novel synthesis of 5,7-dihydrofuro[3,4-d]pyrimidine core is described.