Phenylallyl ethers

More recently, van der Donk and coworkers reported radical cyclizations catalyzed by vitamin B12 using titanium(III) citrate as a stoichiometric reducing agent (Fig. 69, entry 17) [330]. Here /V-allylic 2-(isopropenyl) pyrroles 290 or allyl 2-phenylallyl ethers serve as the starting material in tandem hydrocobaltation/ radical 5-exo cyclization sequences giving dihydropyrrolizine derivatives 291 or 292. The mechanistic course is not completely clear. However, it is assumed that the reactions start with an initial hydrocobaltation of the isopropenyl unit in the presence of the allylic alkene (see Sect. 5.7). The benzylic cobalt intermediate is subject to homolysis of the very weak cobalt-carbon bond and initiates the radical 5-exo cyclization. Interestingly, the fate of the cyclized radical is dependent on the... 

The only kinetic study of acid-catalyzed isomerization of a simple allylic ether was published by Braude and Gore who found that methyl a-phenylallyl ether isomerizes to methyl cinnamyl ether in anhydrous dioxane containing either boron trifluoride or hydrogen chloride. At 25°C, the ether is a quarter to an eighth as reactive as the corresponding alcohol. 

Allylic ethers (165) were first observed as products about ten years ago while allylic ketoalcohols (164) had been isolated much earlier. Investigation of the reaction of biacetyl with a-trideuteriomethylstyrene showed that the simple radical coupling mechanism illustrated above is not correct124) since the deuterium scrambling expected from reaction of a symmetrical 2-phenylallyl radical was not observed in the... 

D 1.047-1.051, refr index 1.539-1.543, flash p 244°F. Misc with chloroform, ether, fixed oils insol in glycerin, water 264°. SYNS ACETIC ACID, CINNAMYL ESTER FEMA No, 2293 Y-PHENYLALLYL ACETATE 3-PHENYL-2-PROPEN-l-YL ACETATE... 

As mentioned already in the polymerization of meth of-phenylacrylate a steri-cally random pdymer was obtained. However, the fraction of heterotactic triad in the polymer did not exceed 50 % under any polymerization conditions with BuLi Initiator (Table 10). On the other hand, methyl a-(p-bromophenyl)acrylate and methyl ce-(p-chlorophenyl)acrylate gave the polymers whose heterotactic contents were 59 and 61 %, respectively, in THF by BuLi at -78 (Table 10). The tacticity was determined by the C-NMR spectra of poly(2-phenylallyI acetate)s derived from the original polymers via pdy(2-phenylallyl alcohol)s. The bulkiness of the o-substituent seems to be important for the heterotactic propagation in these cases, as pointed out by Nozakuia et al. in the formation of heterotactic poty(vinyl alcohol) derived from poly(vinyl trimethylsilyl ether). However, method o-phenylacrylate formed a heterotactic pdymer whose heterotactic content was 66 %, by octylpotassium in THF (Table 10),... 

Poly(l,4-pentadiene-alt-MA), 343, 348, 586 Poly(phenanthrene-alt-MA), 376, 660 Poly(phenylacetylene), MA grafted, 471 Poly(phenylacetylene-co-MA), 335, 660 Poly(2-phenylallyl alcohol-alt-MA), 331, 660 Poly(4-phenyl-l-butene-alt-MA), 340, 341 Poly(/- 1-phenylethyl methacrylate-co-MA), optically active polymer, 383 Poly(/-1-phenylethyl vinyl ether-alt-MA), optically active polymer, 383 Poly(5-phenyl-l-pentene-alt-MA), 340, 341 Poly( l-phenyl-4-pentene- 1-one-alt-MA), 314 Poly(3-phenyl propene-l-alt-MA), 341 Poly(o-phenylstyrene-alt-MA), 373 Poly(2-phenylvinyl alkyl ethers-alt-MA), 318 Poly(2-phenylvinyl alkyl thioethers-alt-MA), 318 Poly(phenyl vinyl ether-alt-MA), 318, 394 Poly(phenyl-o-vinyl formal-alt-MA), 328 Poly(phenyl vinyl ketone-co-MA), physical properties, 290... 

Alkynes may undergo a threefold coupling if suitably substituted. For example, 3-phenylallyl propargyl ether yields an E/Z mixture of 3-diarylmethylene-4-benzylidenetetrahydrofuran, when treated with an aryl halide under Jeffery conditions (Scheme 5-35). This domino reaction (see also 1, Scheme 5-201) starts with an intermolecular coupling (alkyne relay), followed by intramolecular coupling of the intermediate a-ethenylpalladium complex and finally a second intermolecular Heck coupling. 

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