Synthesis of Various Heterocycles Having a Dienamide Moiety by Ring-Closing Metathesis of Ene-ynamides

Abstract

Ring-closing metathesis (RCM) of ynamides, having alkene substituents of various lengths on the side chain, was demonstrated using the second-generation Grubbs catalyst. When the reaction of ene-ynamides was carried out in the presence of 5 mol% of the catalyst, RCM proceeded smoothly to give quinoline or isoquinoline derivatives having a dienamide unit in good yields. Furthermore, RCM of ene-ynamides, having one more carbon on the side chain, proceeded smoothly to provide seven-membered heterocycles having a dienamide component. Similarly, eight-membered heterocycles, diazocine and benzodiazocine, were also synthesized by RCM of ene-ynamides in good yields.

Advanced sol–gel process for efficient heterogeneous ring-closing metathesis

“…Olefin metathesis reactions require a catalyst 28 , for example, the ruthenium-based catalysts (a second-generation Grubbs catalyst and a second-generation Hoveyda-Grubbs catalyst) used in this study 3 , 6 , 15 , 18 , 25 – 27 . Due to catalyst significance, much research has been done to develop an efficient catalyst and efficient catalytic processes.…”

“…Due to catalyst significance, much research has been done to develop an efficient catalyst and efficient catalytic processes. Commonly, homogenous catalysis 4 , 6 , 15 , 18 , 21 – 23 , 25 , 26 has been used; however, owing to their high costs 29 , the ability to recycle the catalyst is very important. As such, it is more efficient and productive to use the catalysts as part of a heterogeneous system, which enables them to be recycled.…”

Sequential Two‐Fold Claisen Rearrangement, One‐Pot Ring‐Closing Metathesis and Cross‐Metathesis as a Route to Substituted Benzo[b]azepine‐2‐one, Benzo[b]azepine and Benzo[b]oxepine Derivatives

“…The study was then extended to the development of a similar pathway for the synthesis of substituted benzoxepine derivatives. Thus, Claisen rearrangement of the allyl ether 24 (Scheme 3), obtained by allylation of commercially available 2-allylphenol (22), proceeded quickly in refluxing N,N-diethylaniline to give the corresponding 2,6-diallylphenol 26 in very good yield. Further O-allylation of the later provided the diene 28.…”

“…[2 -6] Recent progress in various metal-catalyzed ring-forming reactions has facilitated access to these classically otherwise difficult-to-make ring systems. [7][8][9][10][11][12][13][14] In particular, olefin-metathesis mediated transformations, [15][16][17][18][19][20][21][22][23][24][25][26][27][28] either in tandem or in sequence with other named and unnamed reactions, [29,30] have provided rapid access to several structurally embellished entities accommodating the core ring systems. However, comparatively less attention has been paid to develop synthetic methodologies that simultaneously address incorporation of functionalities within the core ring system.…”

Synthesis of Tetrahydroazepines through Silyl Aza-Prins Cyclization Mediated by Iron(III) Salts

“…Classical methods to synthesize this type of heterocycles include Brønsted or Lewis acid-mediated cyclizations, , atom-transfer radical cyclization (ATRC), cycloadditions, , conjugate addition cyclizations, , ring expansions (cyclopropanes, aziridines, azetidines, − 2-cyano-6-oxazolopiperidine), and ring-closing metathesis. − Among the different types of acid-mediated cyclizations, the aza-Prins cyclization is a powerful tool for obtaining nitrogenated heterocycles. It has been widely used for the synthesis of piperidines and pyrrolidines. − However, there are few examples of synthesis of tetrahydroazepines through this methodology. , In 2016, Barbero and co-workers achieved the synthesis of azepane rings, with an exocyclic double bond, through a diastereoselective silyl aza-Prins cyclization mediated by InCl 3 (Scheme ).…”