Ring-Closing Metathesis RCM Reactions

Recent literature examples of sohd-phase RCM reactions, mostly employing the Grubbs ruthenium-based catalyst, were essentially performed in SPOS in order to 

However, conventional fluoride-mediated deprotection release did not work. Re- 

Typicol experimental procedure for RCM on PEG To a solution of PEG-sup-ported N-allyl-(S)-allylglycine (103) methyl ester (0.080 g, 0.019 mmol) in 8 mL of CH2CI2 was added the catalyst RuCl2(=CHPh)(PCy3)2 (3.0 mg, 3.6 pmol). The mixture was stirred at r. t. for 14 h and then precipitated twice from ether. The product was filtered off and dried in vacuo to yield 0.067 g (86%) of the desired compound. 

A 320-member library of cell-permeable molecules, with a tetrahydroox-azepine (THOX) core has been synthesized on a trityl resin by using RCM as the cyclative step [224]. These compounds have been tested in the search of candidate heterodimerizers. 

The resulting phosphine-free solid-supported ruthenium alkylidene (111) was tested as both RCM and CM catalyst in methanol and water. The reactions were run without degassing the solvents and also under an air atmosphere. RCM on various a,ra-heptadienes and CM on unsaturated alcohols worked well, mostly in methanol but also in water. To account for the failure of the same reaction performed with a non-supported catalyst, the authors proposed that the reaction occurs mainly in the resin pores, where the substrate meets a high catalyst concentration, and not in the solvent 

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RCM. See Ring-closing metathesis (RCM) Reaction by-products, removing, 83 Reaction extrusion, 204 Reaction index, 237 Reaction injection molding (RIM), 205 Reaction-in-mold (RIM) nylon, 149 Reaction kinetics, 76, 77 Reaction mechanisms, polyesterification, 66-69... 

Ring Closing Metathesis (RCM) Reactions Used in the Pharmaceutical Industry... 

In the previous section, the cyclopropanation of a glycal to form a bicyclic intermediate was followed by a ring-expansion reaction en route to each oxepine. Presented here are routes that afford oxepines either by ring-closing metathesis (RCM) reactions or by cycloisomerization of terminal alkynes. 

In 1992, Grubbs and coworkers published the synthesis of a new family of me-tallocarbenes and developed their use as catalysts for ring-closing metathesis (RCM) reactions [103-105], Gradually, these compounds were used by a large number of research groups [106-108], because their utilization was close to ideal... 

During the present decade, a wide variety of polycyclic carbacephem derivatives have been reported starting from readily available monocyclic /3-lactams, which after transformation in more functionalized compounds and further cyclization yielded different fused carbacephems. Several approaches for the preparation of fused carbacephem derivatives including cycloaddition reactions such as the [2+2], 1,3-dipolar, and Diels-Alder reactions, as well as transition metal-catalyzed reactions such as the Pauson-Khand and ring-closing metathesis (RCM) reactions have been reported in the literature. 

Ring-closing metathesis (RCM) reactions of iV-alkenylpyridinium salts are possible using Grubbs catalyst and this strategy has been used to access dihydroquinolizinium cations from iV-(2 -butenyl)-a-vinylpyridinium triflates in good yield <20040L4125>. 

Other reactions evaluated by the authors included Wittig-Horner olefination and a series of ring-closing metathesis (RCM) reactions, employing Grubb s II catalyst. In all cases, a reduction in power consumption, increase in yield, and reduction in reaction time were obtained as a result of employing microwave-assisted continuous flow reactions [33],... 

With the pathway to diene 67 secure, our attention was now directed towards the ensuing ring closing metathesis (RCM) reaction to form cyclopentene 68 (Scheme 16). The first-generation Grubbs catalyst 69 was our first port of call, as this was the cheapest of the commercially... 

Dienes can be cyclized in the ring-closing metathesis (RCM) reaction with concomitant formation of volatile olefin side products (usually ethylene) (Fig. 4.12). RCM has been used to make small- and medium-sized rings, including carbocy-... 

Upon a sequential bis(aUenylation)/bis-(oxycyclization) followed by a ring-closing metathesis (RCM) reaction, the synthesis of structurally... 

Shortly after this, Kandula and Kumar" developed a synthetic route to (- )-acaterin by employing Sharpless asymmetric dihydroxylation and Wittig ole-fination as key steps (Scheme 5.2). Singh et al. have reported another synthetic route, in which a ring-closing metathesis (RCM) reaction as a key step was employed (Scheme 5.3), with the synthesis of natural (-)-acaterin 1 being accomplished in an overall yield of 22%. ... 

A sequence of reactions, including the ring closing metathesis (RCM) reaction, leads to a 39-membered ring in the overall yield of 70% as... 

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