Intermolecular hydrogen transfers in 2,3-dihydroimidazol-2-ylidene and 2,3-dihydrothiazol-2-ylidene: a theoretical study

The remarkable stability of N-heterocyclic carbenes has been an area of gre at interest in chemistry. However prototype carbenes of these molecules, i. e. those with hydrogen atoms bearing on the nitrogens. have not been isolat ed as: stable compounds. It is clear from our theoretical study that these prototype carbenes (2.3-dihydroimidazol-2-ylidene and 2.3-dihydrothiazol-3- ylidene) should undergo intermolecular hydrogen transfers (forming imidazol e and thiazole) easily at room temperature. (C) 2001 Elsevier Science Ltd. All rights reserved.