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On the Mechanism of the α-Alkynone Cyclization: A Theoretical Study

✍ Scribed by José Kaneti; Martin Karpf; André S. Dreiding

Publisher
John Wiley and Sons
Year
1982
Tongue
German
Weight
435 KB
Volume
65
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

The acetylene → carbene rearrangement of three model a‐alkynones, namely propynal (1a), 2‐butynal (1b) and butynone (1c) is studied by ab initio double‐zeta, double‐zeta plus polarization and double‐zeta plus self‐consistent electron pairs calculations. Transition states are located by force‐gradient geometry optimization. Calculated minimum energy reaction paths reveal substituent effects on the activation parameters, which indicate that a H‐atom or an alkyl group competes favorably with an acyl group in the [1,2]‐shift from a‐alkynones 1 to the corresponding acylvinylidenes 5.

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