反應(yīng)機(jī)理
季銨堿加熱一般消除含氫較多的β碳上的氫，這個(gè)規(guī)則與Zaitsev規(guī)則相反，稱為霍夫曼規(guī)則（Hofmann規(guī)則）。Hofmann規(guī)則的本質(zhì)是體積效應(yīng)。從空間位阻較小的位點(diǎn)消除。該反應(yīng)是經(jīng)由E1cB或E2機(jī)理進(jìn)行的消除反應(yīng)。當(dāng)季銨堿中β氫有明顯酸性時(shí)，產(chǎn)物為遵守Zaitsev規(guī)則的產(chǎn)物。
反應(yīng)實(shí)例
通過Hofmann消除從樹脂上解離胺。
【Tetrahedron Lett. 2010, 51, 5003–5004】
【Synth. Commun. 2012, 42, 3545–3552】
參考文獻(xiàn)
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編譯自：Name Reactions （A Collection of Detailed Reaction Mechanisms）, Jie Jack Li, Hofmann elimination，page 318.
