Acetylenes as Potential Antarafacial Components in Concerted Reactions. Formation of Pyrroles from Thermolyses of Propargylamines, of a Dihydrofuran from a Propargylic Ether, and of an Ethylidenepyrrolidine from a β-Amino Acetylene.
Acetylenes as Potential Antarafacial Components in Concerted Reactions. Formation of Pyrroles from Thermolyses of Propargylamines, of a Dihydrofuran from a Propargylic Ether, and of an Ethylidenepyrrolidine from a β-Amino Acetylene.
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乙炔作为协同反应中的潜在反面成分。从丙炔胺热解形成吡咯，从丙炔醚热解形成二氢呋喃，以及从 β-氨基乙炔形成亚乙基吡咯烷。
DOI：
10.1002/chin.199401190
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
J. S. Locke
中科院分区：
文献类型：
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作者：
A. Viola;J. J. Collins;N. Filipp;J. S. Locke
乙炔化合物的热环化为在[2+ 2]过程中乙炔键作为前原子组分的能力提供了证据。这种环化反应与通常有利的乙炔反-烯反应竞争。丙炔胺，没有取代基的存在会阻碍紧密的环过渡态，产生中间吡咯，其随后的氢消除提供少量的吡咯。在2-乙基四氢吡喃中同样的过程得到8-氧杂环[3.2]。1]辛烷35%产率。n-甲基-3-己烯-l-胺的相关热反应提供了n-甲基-2-乙基二吡啶在标称的[2S+ 2a+ 28+ 28] M6bius过程中的定量转化，其中乙炔单元是前反应组分。讨论了在这些反应中存在协同性的证据。在我们对需要环过渡态的乙炔化合物的热分子内反应的研究中，1我们遇到了三个反应过程，表明乙炔键在周环反应中充当前环组分的能力。虽然在这三种情况下，我们都不能清楚地描述反应的机制，但考虑到这三种过程，我们提供了令人信服的证据，证明已知或怀疑能够以这种方式起作用的一小部分精选成分必须扩大到包括乙炔键。
A thermal cyclization of acetylenic compounds provides evidence for the ability of acetylenic links to act as antarafacial components in [2+ 2] processes. The cyclization competes with the normally favored acetylenic retro-ene reaction. Propargylic amines, without substituents whose presence would hinder a tight cyclic transition state, yield intermediate pyrrolines whose subsequent hydrogen elimination affords pyrroles in small amounts. The same process in 2-ethynyltetrahydropyran affords 8-oxabicyclo [3.2. 1] octane in 35% yield. A related thermal reaction of N-methyl-3-hexyn-l-amine provides a quantitative transformationto N-methyl-2-ethylidenepyrrolidinein a nominal [2S+ 2a+ 28+ 28] M6bius process, wherein the acetylenic unit is the antarafacial component. Evidence for concertedness in these reactions is discussed.During our investigations into thermal intramolecular reactions of acetylenic compounds which require cyclic transition states, 1 we have encountered three reaction processes indicative of the ability of acetylenic bonds to act as antarafacial components in pericyclic reactions. Although in none of the three cases can we clearly delineate the mechanism of the reaction, a consideration of all three processes provides compelling evidence that the small select group of components, known or suspected of being capable to act in that manner, must be expanded to include the acetylenic linkage.