Metathesis ring closure

The aryl radical cyclization has been successfully used for the preparation of substituted dihydrobenzo[Z)]indoline derivatives [59], An example is shown in Reaction (7.49). The diene 42 was preliminarly subjected to ring-closure metathesis using Grubbs catalyst and then treated with (TMS)3SiH and EtsB at -20 °C, in the presence of air, to provide the compound 43 with an excellent diastereoselectivity. 

Bronsted acidic ionic liquids [HMIM]BF4, [HMIM]TfO, and [HMIM]TsO are effective for proton- and metal-assisted catalytic processes such as the dimerization of methyl acrylate and ring-closure metathesis (Scheme 3) (72J). For example, the acidic [HBIM]BF4 in association with the [Ru( = C = C = CPh2)(/ -cymene) (PCy3)Cl][OTf catalyst afforded a dramatic increase in the activity (100%) and selectivity (100%) for the ring-closure metathesis of A,A-diallyltosylamide. 

Reuse of Catalysts in Ring-Closure Metathesis with an Ionic Tagged Ruthenium Carbene Complex (188)... 

The convergent synthesis is based on the closure of the macrolide ring through a ring closure metathesis reaction that can be performed on a multigram scale (Fig. 48) [128]. Clinical trials are ongoing [129]. 

Base-induced isomerization of propargyl amide 29a gives chiral ynamide 30a, which is subjected to ring-closure metathesis to afford cyclic enamide 31a. Diels-Alder reaction of 31a with dimethyl acetylene dicarboxylate (DMAD) gives quinoline derivative 32. In a similar manner, propargyl amide 29b is converted into ynamide 30b, RCM of which gives bicyclic compounds 31b and 31b in a ratio of 1 to 1 (Scheme 10). 

More examples in this line can be found in the reports of Shea and Carbery. Perez-Gastells and co-workers combined ring-closure metathesis and PKR for the synthesis of tricyclic compounds in one batch. In this approach, a... 

A simple synthetic protocol for the production of (3-lactams fused to a sultam moiety (I and II, Fig. 16) using a ring closure metathesis has been developed [280]. 

Alternatively, ring closure metathesis reaction is applied to the formation of cyclic polymers, although the main chain does not consist of hydrocarbon. Such a method was reported in the preparation of cyclic poly(THF) as shown in Fig. 33 [112]. Such ring-close metathesis was also applied for a preparation of catenane [113]. 

The ruthenium-based metallodendrimer Go-8 was applied as catalyst in a ring-closure metathesis reaction. The activity per metal center of the dendritic catalysts was found to be comparable to that of the corresponding mononuclear catalyst. Unfortunately, the metathesis reaction conditions were not compatible with the nanofiltration membrane set-up used, since a black precipitate was formed in the vessel containing the catalyst. It was found that the conversion to diethyl-3-cyclopentene dicarboxylate product stopped... 

Scheme 8 Synthesis of Van Koten s dendritic ruthenium metathesis catalyst applied in ring-closure metathesis...

Lee, K. et al. Synthesis Using Ring Closure Metathesis and Effect on Nucleoside Transport of a (N)-Methanocarba S-(4-Nitrobenzyl)Thioinosine Derivative. 2.3 2001 [139]... 

Sch 38516 is a natural product with antifungal properties. A synthetic scheme for this compound involves ring-closure metathesis to generate a 14-membered ring. How many carbon atoms are there in the precursor, and what is the other product ... 

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