P-手性膦烷的质子化：通过开环和C-H活化形成膦环烷。
Protonation of P-Stereogenic Phosphiranes: Phospholane Formation via Ring Opening and C-H Activation.
作者信息
Tipker Ryan M, Muldoon Jake A, Jo Jacob, Connors Christopher S, Varga Balazs R, Hughes Russell P, Glueck David S
机构信息
Department of Chemistry, Dartmouth College, 6128 Burke Laboratory, Hanover, New Hampshire 03755, United States.
出版信息
ACS Omega. 2023 Mar 20;8(13):12565-12572. doi: 10.1021/acsomega.3c00885. eCollection 2023 Apr 4.
Protonation of cyclopropanes and aziridines is well-studied, but reactions of phosphiranes with acids are rare and have not been reported to result in ring opening. Treatment of -MesPCHCHR (Mes = 2,4,6-(-Bu)CH, R = Me or Ph, --) or -MesPCHCHPh (-) with triflic acid resulted in regiospecific -Markovnikov C-protonation with ring opening and cyclophosphination of a Mes --Bu group to yield the phospholanium cations [PH(CHCHR)(4,6-(-Bu)-2-CMeCHCH)][OTf] (R = Me or Ph, -), which were deprotonated with NEt to give phospholanes -. Enantioenriched or racemic - both gave racemic . The byproduct [MesPH(CHCHMe)(OH)][OTf] () was formed from - and HOTf in the presence of water. Density functional theory calculations suggested that P-protonation followed by ring opening and hydride migration to C yields the phosphenium ion, [MesP(CHCHMe)][OTf], which undergoes C-H oxidative addition of an --Bu methyl group. This work established a new reactivity pattern for phosphiranes.
环丙烷和氮杂环丙烷的质子化已得到充分研究，但膦环烷与酸的反应却很罕见，且尚未有报道表明会导致开环。用三氟甲磺酸处理 -MesPCHCHR（Mes = 2,4,6-(-Bu)CH，R = Me 或 Ph，--）或 -MesPCHCHPh (-)，会发生区域选择性的 -马尔科夫尼科夫 C-质子化反应，伴随开环以及 Mes --Bu 基团的环膦化反应，生成膦鎓阳离子 [PH(CHCHR)(4,6-(-Bu)-2-CMeCHCH)][OTf]（R = Me 或 Ph，-），用 NEt 对其进行去质子化反应可得到膦环烷 -。对映体富集的或外消旋的 -均得到外消旋的 。副产物 [MesPH(CHCHMe)(OH)][OTf] () 是由 - 和 HOTf 在水存在的情况下形成的。密度泛函理论计算表明，P-质子化后接着开环以及氢化物迁移至 C 会生成磷叶立德离子 [MesP(CHCHMe)][OTf]，它会发生 --Bu 甲基的 C-H 氧化加成反应。这项工作确立了膦环烷的一种新反应模式。
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