Diethyl diallylmalonate

A nuxture of tungsten(Vl) oxytetrachloride (0.43 g, 1.3 mmol), toluene (10 mL), and 2,6-dibromOphenol (0.63 g, 2.5 mmol) is heated under reflux for 1 h and then concentrated under reduced pressure. The solid residue is broken up with a spatula and dried under high vacuum for 15 min. Toluene (75 mL), diethyl diallylmalonate (15.0 g, 62.4 mmol), and tetraethyllead (0.81 g, 2.5 mmol) are added to the crude tungsten complex and the resulting mixture is heated to 90 °C... 

Tab. 11.2 Ru contaminant level for the RCM of diethyl diallylmalonate with catalysts (9) and (10). ...

As shown in Tab. 11.7 for the RCM of diethyl diallylmalonate, the original catalyst (10) suffered complete loss of metathesis activity after only two runs (entry 1). On the other hand, the second generation catalyst (55) retained modest activity in the third consecutive run (entry 2). As in the prior study [18], the addition of a terminal olefin additive was required to extend the catalyst lifetime past four runs (entry 3). Use of triphenylphosphine as a second additive just ten minutes before filtration led to further improvements in activity during catalyst reuse. However, as mentioned previously, the use of additives is somewhat wasteful and exclusive, since... 

Tab. 11.9 RCM of diethyl diallylmalonate with poly-DVB-supported Ru catalysts (64), (65) and (66). ...

During the same period, Nolan showed also that indenylidene complexes are active catalyst precursors in the RCM of dienes. The reactions were performed on the NMR scale and moderate to good yields were obtained for diethyl diallylmalonate. 

Cationic nickel catalysts with monodentate phosphoramidites and Wilke s azaphosp-holene as ligands have been shown to be highly regio- and enantio-selective catalysts for the cycloisomerization of diethyl diallylmalonate (Scheme 78).120... 

In 2005, Piers et al. prepared the 14-electron (14e) phosphonium alkyh-dene ruthenium complex 24. This catalyst displays higher activity in the RCM of diethyl diallylmalonate at 0 °C when compared to the second generation catalyst 3 (> 90% conversion after 2 h for 24 versus 25% conversion after 4 h for 3 and > 90% after 5 h for the Schrock molybdenum-based catalyst) (Eq. 27). RCM reactions of trisubstituted, six-membered ring, or seven-membered ring substrates are catalyzed at room temperature affording good... 

Complexes 53 are efficient catalysts for the homodimerization of 1-octene and styrene. Complex 53a bearing the sterically more demanding l,3-bis(2,6-diisopropylphenyl)-NHC ligand shows a higher reactivity than the mesityl-substituted 53b. These complexes also catalyze the CM of 1-octene or styrene with methyl acrylate ( 80% yield), the RCM of diethyl diallylmalonate at 40 °C ( 95% yield), and the ROMP of cyclooctene at 60 °C ( 90% yield). By GC-MS analysis the presence of free p-cymene was detected in the beginning of the reactions. From these results it may be concluded that the first step of the catalytic cycle is arene decoordination to generate a 12-electron [OsCl(= CHPh)(NHC)] + derivative as the catalytically active species [102],... 

Table 12 Comparison of efficacy of (274) and (275) over many reaction cycles. For the ring closure of diethyl diallylmalonate...

Catalyst Ru-4 exhibits overall superior activity and improved substrate scope relative to catalyst Ru-2. For example, Ru-4 completes simple metathesis reactions, such as the RCM of diethyl diallylmalonate or the ROMP of cyclooctadiene, at rates several orders of magnitude greater than with Ru-2. In addition, whereas catalyst Ru-2 is unreactive toward sterically congested or electronically deactivated substrates, Ru-4 successfully mediates the formation of tetra-substituted olefins in five- and six-mem-bered rings systems [9], as well as CM to form tri-substituted olefins and products containing electron-withdrawing substituents [10]. 

The following German patents have also been taken out for alipliatic acid mercurials Ibid, 246207, behenolic acid esters, stearolio acid ester. Ibid, 264267, aryl hydroxy fatty acids. Ibid, 279199, aminometiiane disulphonic acid. Ibid., 228877, oleic acid ethyl ester, triolein. Ibid., 387850 American Patent, 1457675 diethyl diallylmalonate, diallyb barbituric acid, ethyl dialiylacetate, diethjri o-phenylenediacrylate, diplienio acid and ethyl diphenylamine-2-ca.rboxylate. 

Catalyst 87 (tag on salicylidene oxygen Scheme 1.52) and 88 (tag on salicylidene ring) were evaluated in the RCM of diethyl diallylmalonate at rt using 5 mol.% in 1 h. Catalyst 88 was almost twice as reactive in the 1st run but could not be efficiently recycled, while the less reactive 87 maintained an almost constant activity over four cycles. 

In order to design superior catalyst systems and expand the applications of these first generation catalysts, it was necessary to understand the fundamental mechanism of ruthenium-catalyzed olefin metathesis reactions. Initial investigations focused on the activity of 1 and its derivatives for the catalytic RCM of diethyl diallylmalonate (Eq. 4.14) [86]. These studies revealed that, in all cases, the overall catalytic activity was inhibited by the addition of free phosphine, and that the turnover rate was inversely proportional to the concentration of added phosphine. This indicated that phosphine dissociation was required for catalytic activity, and further suggested that olefin metathesis may be initiated by the substitution of a phosphine ligand with an olefin substrate. 

Similar results were reported by Nolan [20a] addition of 10 mol % of PPI13 to 5 (R = Ph, R = mesityl) significantly decreased the RCM activity of this catalyst, leading to only 50 % conversion in 25 min (95 % conversion after 25 min without added PPh3). Addition of 6 mol % of PCy3 to solutions of 5 (R = Cy, R = mesityl) led to 23 % conversion of diethyl diallylmalonate into the cyclopentene product over the same time interval (92 % conversion after 25 min without added PCy3). 

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