Beilstein J. Org. Chem.2016,12, 43–49, doi:10.3762/bjoc.12.6
Anup Rana Mehmet Emin Cinar Debabrata Samanta Michael Schmittel Department of Chemistry and Biology, Universität Siegen, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany 10.3762/bjoc.12.6 Abstract The mechanism of the thermal cyclization of enyne-carbodiimides 7a–c has been studied computationally
by applying the DFT method. The results indicate that enyne-carbodiimides preferentially follow the C2–C6 (Schmittel) cyclization pathway in a concerted fashion although the Myers–Saito diradical formation is kinetically preferred. The experimentally verified preference of the C2–C6 over the Myers
pathway if the trapping reaction by hydrogen transfer is no more rate determining.
Keywords: DFT computation; diradical; enyne-carbodiimides; hydrogen transfer; thermal cyclization; Introduction
The thermal cyclizations of enediynes [1][2][3][4][5][6], enediallenes [7][8][9][10], bisallenes [11], enyne
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Graphical Abstract
Scheme 1:
Thermal cyclization modes of enyne-carbodiimides 1a–c.