We report a facile and efficient synthesis of spiro[imidazolidine-4,3′-indolin]-2′-imines
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.