Base-promoted formal [4 + 1+1] annulation of aldehyde, N -benzyl amidine and DMSO toward 2,4,6-triaryl pyrimidines

A base-promoted formal [4 + 1+1] annulation of aldehyde, N-benzyl amidine and DMSO was developed, leading to a series of 2,4,6-triaryl pyrimidines in moderate to good yields. Notably, DMSO served as a methine source, which was activated by base rather than either Lewis acid or electrophile. Molecular O2 was the sole eco-friendly oxidant during this procedure.