Zwitterionic 1,3‐Shift Intermediates in the Interconversions of (Thio)carbamoyl Isocyanates and Carbamoyl Iso(thio)cyanates, R 2 N–CX–NCO ⇌ R 2 N–CO–NCX, and in Carbamoylketenes R 2 N–CO–CH=C=O

Cyclic zwitterionic intermediates 3 have been located as reactive intermediates in the thermal 1,3‐shifts of dimethylamino and N ‐ piperidinyl groups in carbamoyl isocyanates, carbamoyl isothiocyanates and carbamoylketenes at the B3LYP, M06‐2X and MP2 computational levels of theory. The zwitterion formed in the course of the ketene ⇌ ketene rearrangement shows the highest stabilization (by about 3–5 kcal/mol). The interconversions of carbamoyl isocyanates and isothiocyanates should occur readily at or near room temperature with activation barriers in the range 23–30 kcal/mol, and the ketene ⇌ ketene interconversion is expected well below room temperature with an activation barrier of ca. 10 kcal/mol.