Heme compound II models in chemoselectivity and disproportionation reactions
- 주제(기타) Chemistry, Multidisciplinary
- 설명문(일반) [Gupta, Ranjana; Li, Xiao-Xi; Seo, Mi Sook; Lee, Yong-Min; Fukuzumi, Shunichi; Nam, Wonwoo] Ewha Womans Univ, Dept Chem & Nano Sci, Seoul 03760, South Korea; [Lee, Youngseob; Cho, Kyung-Bin] Jeonbuk Natl Univ, Dept Chem, Jeonju 54896, South Korea; [Yanagisawa, Sachiko; Kubo, Minoru] Univ Hyogo, Grad Sch Life Sci, Kobe, Hyogo 6781297, Japan; [Sarangi, Ritimukta] Stanford Univ, SLAC Natl Accelerator Lab, Stanford Synchrotron Radiat Lightsource, Stanford, CA 94023 USA
- 등재 SCIE, SCOPUS
- OA유형 Green Published, gold
- 발행기관 ROYAL SOC CHEMISTRY
- 발행년도 2022
- 총서유형 Journal
- URI http://www.dcollection.net/handler/ewha/000000191187
- 본문언어 영어
- Published As https://doi.org/10.1039/d2sc01232d
- PubMed https://pubmed.ncbi.nlm.nih.gov/35694346
초록/요약
Heme compound II models bearing electron-deficient and -rich porphyrins, [Fe-IV(O)(TPFPP)(Cl)(-) (1a) and [Fe-IV(O)(TMP)(Cl)](-) (2a), respectively, are synthesized, spectroscopically characterized, and investigated in chemoselectivity and disproportionation reactions using cyclohexene as a mechanistic probe. Interestingly, cyclohexene oxidation by la occurs at the allylic C-H bonds with a high kinetic isotope effect (KIE) of 41, yielding 2-cyclohexen-1-ol product; this chemoselectivity is the same as that of nonheme iron(IV)-oxo intermediates. In contrast, as observed in heme compound I models, 2a yields cyclohexene oxide product with a KIE of 1, demonstrating a preference for C = C epoxidation. The latter result is interpreted as 2a disproportionating to form [Fe-IV(O)(TMP+.)](+) (2b) and Fe-III(OH)(TMP), and 2b becoming the active oxidant to conduct the cyclohexene epoxidation. In contrast to 2a, la does not disproportionate under the present reaction conditions. DFT calculations confirm that compound II models prefer C-H bond hydroxylation and that disproportionation of compound II models is controlled thermodynamically by the porphyrin ligands. Other aspects, such as acid and base effects on the disproportionation of compound II models, have been discussed as well.
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