Ring-Expansion Reactions of Epoxy Amides and Enamides: Functionalized Azetidines, Dihydrofurans, Diazocanes, or Dioxa-3-azabicyclonon-4-enes?
作者:Suraj、K. C. Kumara Swamy
DOI:10.1021/acs.joc.2c00268
日期:2022.5.20
3-dihydrofurans, or the unorthodox dioxa-3-azabicyclonone-4-ene motifs are the products from transition metal-free reaction between N-oxiranylmethyl benzenesulfonamide and β-chloro-cinnamaldehyde, depending on whether one uses either NaI/K2CO3 or LiBr/K2CO3. These ring expansion reactions involve enamide (X-ray evidence) derived from N-oxiranylmethyl benzenesulfonamide and β-chloro-cinnamaldehyde as
功能化的氮杂环丁烷、2,3-二氢呋喃或非正统的二氧杂环己烷-3-氮杂双环酮-4-烯基序是N-环氧乙烷基甲基苯磺酰胺和 β-氯-肉桂醛之间的无过渡金属反应的产物,具体取决于是否使用 NaI /K 2 CO 3或 LiBr/K 2 CO 3。这些扩环反应涉及衍生自N-环氧乙烷基甲基苯磺酰胺和 β-氯肉桂醛作为中间体的烯酰胺(X 射线证据) 。N-环氧乙烷基甲基苯磺酰胺本身在加热时产生易于分离的结晶异构重氮杂环烷,其可通过X-射线晶体学表征。
Cobalt‐Catalyzed Cascade Reaction of Ynamides and 1,3‐Dicarbonyl Compounds for Selective Synthesis of Differently Sized
<i>N</i>
‐Heterocycles
作者:Biao Zhang、Xu‐Heng Yang、Jian Huang、Cheng‐an Tao、Jianfang Wang
DOI:10.1002/adsc.202201002
日期:2023.3.7
manifold with various 1,3-dicarbonylcompounds and halogenated N-allyl ynamides was accomplished under alkaline reaction conditions, facilitating the synthesis of differently sized N-heterocycles. A large array of products was prepared to demonstrate the selective synthesis of N-heterocycles of different ring sizes (5-, 6-, and 7-membered rings) via cobalt catalysis. The reaction has broad substrate
Based on some very recent results on Fe-catalyzed boron-source-dependent regiodivergent hydroborations of internalalkynes, we report here a boron-source-dependent but also ligand-dependent mechanistic trichotomy in borylative cyclizations. The choice of ligand plus boron source allows the synthesis of three isomeric borylative cyclization products starting from a common substrate and using the same
Asymmetric Organocatalytic Allylic Substitution of Morita–Baylis–Hillman Carbonates with Allylamines for the Synthesis of 2,5-Dihydropyrroles
作者:Wangsheng Sun、Xiaozhou Ma、Liang Hong、Rui Wang
DOI:10.1021/jo2011522
日期:2011.10.7
The asymmetric allylic substitution reaction of MBH carbonates with allylamines has been developed, which affords N-allyl-beta-amino-alpha-methylene esters in high yields and enantioselectivities. After a subsequent ring-closure metathesis of the products, a series of optically active 2,5-dihydropyrroles could be obtained smoothly in high yields without any loss of enantioselectivity. Finally, a tentative mechanism for rationalization of the reaction has been proposed.