Rearrangements and interconversions of heteroatom-substituted isocyanates, isothiocyanates, nitrile oxides, and nitrile sulfides, RX-NCY and RY-CNX.

摘要: Isocyanates and isothiocyanates of the type RX-NCY (X Y = O or S) isomeric nitrile oxides sulfides RY-CNX are highly reactive compounds. A number potential 1,4-shifts substituent groups R-Y-CNX → R-X-N═C═Y, 1,3-shifts R-C(═Y)-N═X 1,2-shifts have been evaluated computationally. The results obtained for relatively new functional MPW1K well-established B3LYP, together with a triple-ζ quality basis set, very similar. 1,3- 1,4-halogen shifts in title compounds usually exothermic possess low activation barriers. 1,3-Aryl feasible 5e 6e (Ar-CO-NSO(2) Ar-SO(2)-NCO) barriers less than 40 kcal/mol. Additionally, several 1,4-hydrogen 1,4-methyl-shift methoxynitrile sulfide MeO-CNS to methylsulfenyl isocyanate MeS-NCO (4c 6c) potentially feasible. 1,2-shift reactions 4b 5b (HO-NCS H-CS-NO) 4c 5c (Ar-O-CNS→ Ar-CO-NS) good candidates experimental observation energies around 30