7. MCR and functionalized isonitriles

7.1 Toluene sulfonyl methyl isonitrile

The chemistry of toluene sulfonyl methyl isonitrile (TosMIC) and its derivatives has been extensively studied by Van Leusen's team [133]. The presence of two electron-withdrawing groups on the same carbon greatly increases the acidity of these compounds. After deprotonation by weak bases, the carbanion formed can then react with various electrophiles. The use of polarized double bonds such as imines and carbonyl compounds can lead to heterocycles via an aldolization (or Mannich reaction)/cyclization/prototropy/β-elimination sequence (figure 72 ) [134].