PHOTOCHEMICAL P-450 OXYGENATION OF CYCLOHEXENE WITH WATER SENSITIZED BY DIHYDROXY-COORDINATED (TETRAPHENYLPORPHYRINATO)ANTIMONY(V) HEXAFLUOROPHOSPHATE
PHOTOCHEMICAL P-450 OXYGENATION OF CYCLOHEXENE WITH WATER SENSITIZED BY DIHYDROXY-COORDINATED (TETRAPHENYLPORPHYRINATO)ANTIMONY(V) HEXAFLUOROPHOSPHATE
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二羟基配位（四苯基卟啉）六氟磷酸锑 (V) 光化学 P-450 水敏化环己烯氧化
DOI：
10.1021/ja971371r
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发表时间：
1997
影响因子：
15
通讯作者：
H. Inoue
中科院分区：
文献类型：
--
作者：
S. Takagi;Minako Suzuki;T. Shiragami;H. Inoue
近年来，关于可见光分解水，如与人工光合作用有关的氢或氧的释放的研究已被广泛报道。1特别是，已经成功实现了高效的析氢系统。2现在很多注意力转移到水的氧化上，并集中在水分子如何被纳入光氧化还原系统的氧化末端。3，4我们一直在研究光化学氧化还原反应系统，该系统实际上可以在可见光照射下掺入水分子。4.已报道了二甲氧基配位的锑卟啉[SbVTPP（OMe）2] Br敏化的环己烯的高效光化学氧化反应。5反应的关键步骤是三重态卟啉被K_2PtCl_6氧化猝灭产生的阳离子自由基[SbV-TPP（OMe）_2] Br向环己烯的单电子转移。由于K2 PtCl 6被发现是一个有效的电子受体激发SbVTPP，轴向甲氧基配体的羟基取代，预计通过脱质子化的卟啉阳离子自由基的轴向羟基的氧化反应产生另一个关键的中间体金属-氧代配合物。4.本文报道了水作为轴向卟啉配体的双电子氧化活化与环己烯的光化学氧化反应。金属-氧代型络合物被认为是氧化反应中的关键中间体，该氧化反应可被称为“光化学P-450反应”。（0.1 M），K2PtCl6（5× 10-4 M）和[SbVTPP（OH）2] PF 6（550和420 nm辐照分别为3.3× 10-5和1.0× 10-5 M）（2/1%（v/v））作用60 min，K2 PtCl 6完全消失，而卟啉几乎保持不变。K_2PtCl_6消失的量子产率为0.2，与氧化产物的量子产率相同。主要产物为2-环己烯醇（34%）、1，2-二氯环己烷（36%）、2-氯环己醇（顺式12%;反式8%）、环氧环己烷（2%）以及少量的3，3′-双环己烯、3-乙酰胺基环己烯和环己酮。7 K2 PtCl 6和[SbVTPP（OH）2]-PF 6对于环己烯的光化学氧化都是必需的。ZnIITPP作为敏化剂代替SbVTPP没有得到任何产物。反应的净化学反应可以用方程1-4表示。
Recently, many studies on water splitting, such as hydrogen or oxygen evolution by visible light in relation to artificial photosynthesis have been extensively reported. 1 In particular, highly efficient hydrogen evolution systems have been successfully achieved. 2 Much attention is now shifted to the oxidation of water and is focused on how a water molecule can be incorporated into the oxidation terminal end of photoredox systems. 3, 4 We have been examining photochemical redox reaction systems that could actually incorporate a water molecule upon visible light irradiation. 4 An efficient photochemical oxygenation reaction of cyclohexene sensitized by dimethoxycoordinated antimony (V) porphyrin [SbVTPP (OMe) 2] Br has already been reported. 5 The key step of the reaction was a single electron transfer to cyclohexene from the cation radical of [SbV-TPP (OMe) 2] Br generated by oxidative quenching of the triplet porphyrin by K2PtCl6. Since K2PtCl6 was revealed to be an efficient electron acceptor for excited SbVTPP, a substitution of the axial methoxyl ligands by hydroxyl groups is expected to generate another key intermediate metal-oxo complex for the oxygenation reaction through deprotonation of the axial hydroxyl group of the porphyrin cation radical. 4 In this paper, we report the photochemical oxygenation of cyclohexene coupled with two-electron oxidative activation of water as an axial porphyrin ligand. A metal-oxo type complex is supposed to be a key intermediate in the oxygenation reaction which could be called a “photochemical P-450 reaction”.Upon visible light irradiation6 of the reaction mixture containing cyclohexene (0.1 M), K2PtCl6 (5× 10-4 M), and [SbVTPP (OH) 2] PF6 (3.3× 10-5 and 1.0× 10-5 M for the irradiations at 550 and 420 nm, respectively) in acetonitrilewater (2/1%(v/v)) for 60 min, K2PtCl6 completely disappeared, while the porphyrin remained almost unchanged. The quantum yield of disappearance of K2PtCl6 was 0.2, which was identical with that of the oxygenated products. The major products were cyclohex-2-enol (34%), 1, 2-dichlorocyclohexane (36%), 2-chlorocyclohexanol (cis, 12%; trans, 8%), cyclohexene oxide (2%), and small amounts of 3, 3′-bicyclohexenyl, 3-acetaminocyclohexene, and cyclohexanone. 7 Both K2PtCl6 and [SbVTPP (OH) 2]-PF6 were necessary for the photochemical oxygenation of cyclohexene. ZnIITPP as a sensitizer instead of SbVTPP did not afford any products. The net chemistry of reaction could be expressed as in eqs 1-4.