Thermal or Lewis acid-promoted electrocyclisation and hetero Diels-Alder cycloaddition of α,β-unsaturated (conjugated) carbodiimides: A facile synthesis of nitrogen-containing heterocycles
α,β-Diarylvinyl- and α-styryl-carbodiimides, prepared by the aza-Wittig reaction of iminophosphoranes with isocyanates, underwent either 6π-electrocyclisation upon heating or a Diels-Alder reaction under thermal or Lewis acid-promoted conditions with appr
CONJUGATED HETEROCUMULENES. SYNTHESIS OF C=C-CONJUGATED CARBODIIMIDES BY A WITTIG-TYPE REACTION OF IMINOPHOSPHORANES WITH ISOCYANATES AND THEIR CYCLOADDITIONS
A Wittig-type reaction of N-(1,2-diarylethenyl)iminophosphoranes with isocyanates gave C=C-conjugated carbodiimides, which were utilized in the synthesis of heterocycles.