Substituent effects on the Bergman cyclization of (Z)-1,5-hexadiyne-3-enes: a systematic computational study

✍ Scribed by Matthias Prall; Alexander Wittkopp; Andrey A. Fokin; Peter R. Schreiner

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 165 KB
• Volume: 22
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.1114

✦ Synopsis

Abstract

The effects of several substituents (BH~2~, BF~2~, AlH~2~, CH~3~, C~6~H~5~, CN, COCH~3~, CF~3~, SiH~3~, NH~2~, NH~3~^+^, NO~2~, PH~2~, OH, OH~2~^+^, SH, F, Cl, Br) on the Bergman cyclization of (Z)‐1,5‐hexadiyne‐3‐ene (enediyne, 3) were investigated at the Becke–Lee–Yang–Parr (BLYP) density functional (DFT) level employing a 6‐31G* basis set. Some of the substituents (NH~3~^+^, NO~2~, OH, OH~2~^+^, F, Cl, Br) are able to lower the barrier (up to a minimum of 16.9 kcal mol^−1^ for difluoro‐enediyne 7rr) and the reaction enthalpy (the cyclization is predicted to be exergonic for OH~2~^+^ and F) compared to the parent system giving rise to substituted 1,4‐dehydrobenzenes at physiological temperatures. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1605–1614, 2001