Nonstatistical Dynamic Effects in the Thermal C2–C6 Diels–Alder Cyclization of Enyne–Allenes
摘要:
The Diels-Alder (DA) reaction channel of the thermal C-2-C-6 (Schmittel) cyclization of enyne-allenes is studied computationally and experimentally evaluating the influence of temperature on product ratios. Remote substituents at the alkyne terminus influence the mechanism of the C-2-C-6/DA cyclization steering it either to a stepwise or a concerted course. Temperature independent product ratios, selectivity of product formation, and computational results obtained at (U)BLYP/6-31G(d) level unveil a mechanism that is strongly controlled by nonstatistical dynamics.
Tunable Synthesis of Indeno[1,2-<i>c</i>]furans and 3-Benzoylindenones via FeCl<sub>3</sub>-Catalyzed Carbene/Alkyne Metathesis Reaction of <i>o</i>-Alkynylbenzoyl Diazoacetates
作者:Bin Li、Nana Shen、Yujie Yang、Xinying Zhang、Xuesen Fan
DOI:10.1021/acs.orglett.0c03882
日期:2021.1.15
An efficient synthesis of indeno[1,2-c]furan and 3-benzoylindenone derivatives through a FeCl3-catalyzed carbene/alkyne metathesis reaction of o-alkynylbenzoyl diazoacetates is presented. Mechanistically, the key intermediate, vinyl iron carbene, is formed by 5-exo-dig carbocyclization and terminated with a formal [3 + 2] cycloaddition or carbonylation. To the best of our knowledge, this is the first
提出了一种通过FeCl 3催化邻炔基苯甲酰基重氮乙酸酯的卡宾/炔烃复分解反应有效合成茚并[1,2- c ]呋喃和3-苯并亚吲哚酮衍生物的方法。从机理上讲,关键中间体乙烯基铁卡宾通过5 -exo-dig碳环化反应形成,并以正式的[3 + 2]环加成或羰基化作用终止。据我们所知,这是第一个将FeCl 3用作卡宾/炔烃复分解反应的催化剂的例子。最后,进行衍生化反应以展示产品的价值。