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Regioselectivity and Reactivity of Intramolecular [2+2] Cycloaddition Reactions of Acyl Ketenes: Experimental and Theoretical Studies
Synlett ( IF 1.7 ) Pub Date : 2018-07-10 , DOI: 10.1055/s-0037-1610198 Mahboobeh Zahedifar 1 , Hassan Sheibani 2 , Vahid Saheb 2
Synlett ( IF 1.7 ) Pub Date : 2018-07-10 , DOI: 10.1055/s-0037-1610198 Mahboobeh Zahedifar 1 , Hassan Sheibani 2 , Vahid Saheb 2
Affiliation
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The regioselectivity of the intramolecular [2+2] cycloaddition reaction of acyl ketenes formed from metastable mesoionic 1,3-oxazinium-4-olates was investigated by experimental and theoretical methods. The ring opening of the mesoionic N -allyl-2-(2-arylvinyl)-1,3-oxazinium-4-olates led to the formation of unstable acyl ketenes. Although there are four possible paths for an intramolecular [2+2] cycloaddition reaction involving the two double bonds (vinyl and allyl), only the intramolecular [2+2] criss-cross cycloaddition reaction through the vinyl double bond occurred to give 3-allyl-3-azabicyclo[3.1.1]heptane-2,4,6-trione derivatives. These products were not formed when a strongly electron-withdrawing group was present on the aryl group of acrylamides or benzamides. To understand the mechanism of the reaction, density functional theory calculations at the M06-2X/6-31+G(d) level were performed. These revealed that the formation of some preliminary intermediates plays a significant role in the formation of mesoionic 1,3-oxazinium-4-olates.
中文翻译：
酰基烯酮分子内 [2+2] 环加成反应的区域选择性和反应性：实验和理论研究
通过实验和理论方法研究了由亚稳态介离子 1,3-oxazinium-4-olates 形成的酰基烯酮的分子内 [2+2] 环加成反应的区域选择性。介离子 N-allyl-2-(2-arylvinyl)-1,3-oxazinium-4-olates 的开环导致不稳定酰基烯酮的形成。尽管涉及两个双键（乙烯基和烯丙基）的分子内 [2+2] 环加成反应有四种可能的路径，但只有通过乙烯基双键的分子内 [2+2] 交叉环加成反应发生了 3-烯丙基-3-氮杂双环[3.1.1]庚烷-2,4,6-三酮衍生物。当丙烯酰胺或苯甲酰胺的芳基上存在强吸电子基团时，不会形成这些产物。为了理解反应机理，进行了 M06-2X/6-31+G(d) 水平的密度泛函理论计算。这些表明一些初步中间体的形成在中离子 1,3-oxazinium-4-olates 的形成中起着重要作用。
更新日期：2018-07-10
中文翻译：
酰基烯酮分子内 [2+2] 环加成反应的区域选择性和反应性：实验和理论研究
通过实验和理论方法研究了由亚稳态介离子 1,3-oxazinium-4-olates 形成的酰基烯酮的分子内 [2+2] 环加成反应的区域选择性。介离子 N-allyl-2-(2-arylvinyl)-1,3-oxazinium-4-olates 的开环导致不稳定酰基烯酮的形成。尽管涉及两个双键（乙烯基和烯丙基）的分子内 [2+2] 环加成反应有四种可能的路径，但只有通过乙烯基双键的分子内 [2+2] 交叉环加成反应发生了 3-烯丙基-3-氮杂双环[3.1.1]庚烷-2,4,6-三酮衍生物。当丙烯酰胺或苯甲酰胺的芳基上存在强吸电子基团时，不会形成这些产物。为了理解反应机理，进行了 M06-2X/6-31+G(d) 水平的密度泛函理论计算。这些表明一些初步中间体的形成在中离子 1,3-oxazinium-4-olates 的形成中起着重要作用。
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