Journalartikel

Jahr der Veröffentlichung: 2011

Seiten: 13614-13621

Zeitschrift: Journal of the American Chemical Society

Bandnummer: 133

Heftnummer: 34

DOI Link: https://doi.org/10.1021/ja204507j

Verlag: American Chemical Society

Abstract: 

Cyclopropylhydroxycarbene was generated by high-vacuum flash pyrolysis
of cyclopropylglyoxylic acid at 960 °C. The pyrolysis products were
matrix-isolated in solid Ar at 11 K and characterized by means of IR
spectroscopy. Upon photolysis, the carbene undergoes ring expansion,
thereby paralleling the reactivity of other known cyclopropylcarbenes.
The ring expansion product, cyclobut-1-en-1-ol, was characterized for
the first time. Matrix-isolated cyclopropylhydroxycarbene undergoes
[1,2]H-tunneling through a barrier of approximately 30 kcal·mol^–1,
yielding cyclopropylcarboxaldehyde. The cyclopropyl moiety acts as a
π-donor and increases the half-life by almost a factor of 10 compared to
parent hydroxymethylene, resulting in a temperature-independent
half-life of τ = 17.8 h at both 11 and 20 K. Hence,
cyclopropylhydroxycarbene is the first hydroxycarbene that differs from
other members of its family by a significantly prolonged half-life. As
expected, the O-deuterated analogue does not show tunneling. Our
findings are rationalized by accurate CCSD(T)/cc-pVnZ (n =
D, T)//M06-2X/6-311++G(d,p) computations. The half-life of
cyclopropylhydroxycarbene was verified by tunneling computations
employing the Wentzel–Kramers–Brillouin formalism. By comparison with
other experimentally known hydroxycarbenes, we determine the electronic
donor capabilities of the carbenes’ substituents to be a dominant factor
governing their half-lives.

Harvard-Zitierstil: Ley, D., Gerbig, D., Wagner, J., Reisenauer, H. and Schreiner, P. (2011) Cyclopropylhydroxycarbene, Journal of the American Chemical Society, 133(34), pp. 13614-13621. https://doi.org/10.1021/ja204507j

APA-Zitierstil: Ley, D., Gerbig, D., Wagner, J., Reisenauer, H., & Schreiner, P. (2011). Cyclopropylhydroxycarbene. Journal of the American Chemical Society. 133(34), 13614-13621. https://doi.org/10.1021/ja204507j