open access

https://hdl.handle.net/2115/94069

trans-Cyclooctenes as Scavengers of Bromine Involved in Catalytic Bromination

英語

trans-cyclooctene

2024-02-07

Wiley-Blackwell

Chemistry-A European journal

30(8)

Scavengers that capture reactive chemical substances are used to prevent the decomposition of materials. However, in the field of catalysis, the development of scavengers that inhibit background pathways has attracted little attention, although the concept will open up an otherwise inaccessible reaction space. In catalytic bromination, fast non-catalyzed background reactions disturb the catalytic control of the selectivity, even when using N-bromoamide reagents, which have a milder reactivity than bromine (Br-2). Here, we developed a trans-cyclooctene (TCO) bearing a 2-pyridylethyl group to efficiently retard background reactions by capturing Br-2 in bromocyclization using N-bromosuccinimide. The use of less than a stoichiometric amount of the TCO was sufficient to inhibit non-catalyzed reactions, and mechanistic studies using the TCO revealed that in situ-generated Br-2 provides non-catalyzed reaction pathways based on a chain mechanism. The TCO is useful as an additive for improving enantioselectivity and regioselectivity in catalytic reactions. Cooperative systems using the TCO with selective catalysts offer an alternative strategy for optimizing catalyst-controlled selectivity during bromination. Moreover, it also served as an indicator of Br-2 involved in catalytic reaction pathways; thus, the TCO was useful as a probe for mechanistic investigations into the involvement of Br-2 in bromination reactions of interest.

学術雑誌論文

Accepted Manuscript

This is the peer reviewed version of the following article: R. Murata, K. Shitamichi, M. Hiramatsu, S. Matsubara, D. Uraguchi, K. Asano, Chem. Eur. J. 2024, 30, e202303399., which has been published in final form at https://doi.org/10.1002/chem.202303399. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.

0947-6539