Shifting Access from Pyrimidine-Spirofused to Fused Benzoheterocycles by Modifying the Activated Group Position

The synthesis of pyrimidine-spirofused indolines from 1,3,5-triazinanes with 2-sulfonyliminoindolines has been achieved under catalyst- and additive-free conditions, in which five atoms of 1,3,5-triazinanes were introduced to the spiro-annulation products via a (5+1) pathway. Subsequently, this strategy was extended to 3-aminoindoles and 3-aminobenzothiophenes, but a different reaction pathway (3+3) was observed. In these cases, three-atoms of 1,3,5-triazinanes were incorporated into pyrimidine-fused indoles/benzothiophenes. These two transformations demonstrate the potential and versatility of 1,3,5-triazinanes to construct nitrogen-heterocycles. + image