Allyl methyl ether

Carbonylation of allylic alcohols requires severe conditions[248]. The carbonylation of allylic alcohols proceeds smoothly in the presence of LiCl and Ti(IV) isopropoxide[249j. The allylic methyl ether 394 can be carbonylated with the use of PdCl2[250] or 7r-allylpalladium coordinated by BF4, PF, and... 

Various functionalized allylic boronates have been prepared.58 Z-3-Methoxy derivatives can be prepared by initiation of allyl methyl ether and substitution.59... 

Dibenzyl ether reacted with Mg after five days of reflux in THF to give phenylacetic acid in 42% yield after carbonation. Maercker(99) was able to obtain a 15% yield of 3-butenoic acid from allyl methyl ether after 56 h of reflux. 

Method c. The dibromide is converted into the corresponding allylic methyl ethers by treatment with NaOH as described previously. 

Metallated allylic ethers can also be used as partners in allylzincations of alkenyl-metals144. Allyl methyl ether could be metallated with s-BuLi in ether provided that TMEDA was present and, after transmetallation with ZnBr2, addition to the alkenyl-lithium derived from 205 proceeded slowly at room temperature. Nevertheless, after hydrolysis the corresponding allylic ether 227 was obtained with high diastereoselectivity (equation 110)146. 

Chiral solvomercuration was accomplished by carrying out the reaction of alkenes with Hg(OAc)2 in the presence of chiral quaternary ammonium salts synthesized from natural ephedrine.642 Chiral secondary alcohols may be isolated with ee values up to 96%. Chiral nitrogen-containing diselenides are transformed by perox-odisulfate to selenium electrophiles, which may add to alkenes to form oxyseleny-lation products. These are, however, not isolated but oxidized to induce oxidative p-hydride elimination to afford chiral allyl methyl ethers with ee values up to 75%.643... 

In another study several simple silenes RR Si=CH2 (R, R = Me, Vinyl etc.) were formed by laser-powered pyrolysis and were found to form linear polymers, in contrast to the usual behavior of silenes which yield cyclodimers when formed by conventional thermolysis techniques16. Reactions of the silenes in the presence of several monomers such as vinyl acetate, allyl methyl ether and methyl acrylate were also studied. Laser-induced decomposition of silacyclobutane and 1,3-disilacyclobutane gave rise to silenes and other oxygen-sensitive deposits17,18. 

Benzyl methyl ether or allyl methyl ethers can be selectively metalated at the benzylic/allylic position by treatment with BuLi or sBuLi in THF at -40 °C to -80 C, and the resulting organolithium compounds react with primary and secondary alkyl halides, epoxides, aldehydes, or other electrophiles to yield the expected products [187, 252, 253]. With allyl ethers mixtures of a- and y-alkylated products can result [254], but transmetalation of the lithiated allyl ethers with indium yields y-metalated enol ethers, which are attacked by electrophiles at the a position (Scheme 5.29). Ethers with ft hydrogen usually undergo rapid elimination when treated with strong bases, and cannot be readily C-alkylated (last reaction, Scheme 5.29). Metalation of benzyl ethers at room temperature can also lead to metalation of the arene [255] (Section 5.3.11) or to Wittig rearrangement [256]. Epoxides have been lithiated and silylated by treatment with sBuLi at -90 °C in the presence of a diamine and a silyl chloride [257]. 

The formation of the pentacoordinate species (XX) is also supported by the reaction of the triphenylphosphine derivative (XXI) with CO in methanol to give, besides allyl methyl ether, methyl butenoate (14). 

Dimethylcyclopro- Allyl methyl ether, allyl cyclopropanecarboxylates 21 panecarboxylate... 

Ally I ketene dithioacetals. In the presence of these two reagents, ketene dithioacetals (1) react with allyl methyl ethers to provide allyl-substituted ketene dithioacetals (equation I). The combination of ClSi(CH3)3 and SnCl2 is an equally... 

Asymmetric allylboration has also been applied to y-methoxyallyl derivatives. Isomerically pure (Z)-y-methoxyallyldiisopinocampheylborane (rf31), prepared from Ipc2lSOMe and the lithium anion of allyl methyl ether, reacts with various aldehydes to afford the yyn - j-m e (boxy homoallylic alcohol (32a) in a highly regio- and stereoselective manner17 (Scheme 3.In). This one-pot synthesis of enantiomerically pure 1,2-diol derivatives went as smoothly as the asymmetric Brown crotylation, affording products with uniformly high diastereoselectivity. 

An electrochemical synthetic process (see Qiapter 7.1, this volume) has been reported which requires only a catalytic amount of the selenating agent, and converts an alkene to the allylic alcohol in an aqueous cell, or to the allylic methyl ether if the electrolysis is run in methanol, as in equaticxi (9).t ... 

Methoxylation 0/ allylic alcohols. This complex catalyzes the methoxylation of steroidal allylic alcohols to rearranged allyl methyl ethers. ... 

Allyl methyl ethers of the type shown in equation (II) are also oxidized to a-phenylseleno aldehydes. 

Terminal 1,3-dienes. Palladium(II) acetate combined with PiCsH,), is an effective catalyst for conversion of allylic acetates or allylic phenyl ethers into terminal dienes. Allylic methyl ethers or alcohols do not undergo this elimination. Example ... 

The highest diastereoselectivity of asymmetric methoxyselenenylation of alkenes was achieved using the ferrocenylselenium triflates in excellent chemical yields [5gj. For example, the stoichiometric reaction of the chiral ferrocenylselenium triflate 41, prepared from the chiral diferrocenyl diselenide 2, with traus- -methylstyrene afforded the corresponding methoxyselenenylated product in high chemical yield with excellent diastereoselectivity (up to 98 % de). Fukuzawa and co-workers employed the diferrocenyl diselenide 2 for the catalytic asymmetric oxidation of, y-unsaturated esters and traus- -methylstyrene to the corresponding optically active allylic methyl ethers with moderate enantio-selectivity (Scheme 24) [27]. The allylic ethers were produced from 4-phenyl-3-butenoic acid esters in 70-78% yield with 17-22% ee. 

Similarly, Tiecco and co-workers carried out the catalytic one-pot conversion of a, y-unsaturated ester into the corresponding allylic methyl ether using the... 

Tolman has shown that the equilibrium constants for the reactions of 38 substituted alkenes with Ni[P(0-o-tolyl)3]3 (13) in benzene, to form (ENE)bis(tri-o-tolylphosphite)nickel complexes (14), are sensitive to the structure of the alkene (equation 13). Values of K[ at 25 °C vary from 10 to 4 x 10. The stability of the complex is enhanced by electron-withdrawing substituents such as cyano and car-boxy and lowered by alkyl groups. That resonance involving unshared electrons on the oxygen of an al-koxy group overpowers the inductive effect is indicated by the relative values of Ki for allyl methyl ether, 1-hexene and vinyl butyl ether which diminish in that order by factors of 3 1 0.006. 

The enhanced reductive power of Lewis acid/LAH mixtures observed with benzyl substituents is reflected in allyl compounds. Thus allyl methyl ethers are readily demethoxylated with LAH/TiCU (equation 49), with complete rearrangement of the double bond and some (Z)-selectivity. Allyl alcohols are reduced to alkenes with the same reagent or with LAH/AICI3 (equation 50). With both these reagents double bond migration was observed to varying degrees as well as diene formation. Primary allyl alcohols have been reduced to alkenes with titanocene and LAH (equation 51). ... 

Whereas ethylmagnesiation of allyl alcohols affords the syn diol with 95 5 diastereoselectivity, the same reaction on the allyl methyl ether affords predominantly the anti diastereomer with 90 10 selectivity [92] (Scheme 7-80). The reversal of stereoselectivity was attributed to the association of the magnesium alkoxide (and not of ethers) with the zirconium reagent (Scheme 7-80). 

An allylzinc bromide bearing an alkoxy group can also be used for example, if the metallated allyl methyl ether reacts [101] with an ( ) or (Z) functionalized vinyllithium, the... 

The same year, it was noted by Commer on [54] that the use of the Cu Br catalysis for the reaction of Grignard reagents with allyl methyl ethers lead to the mixture of Sn2 and Sn2 products, according to the steric hindrance of the substrate and the geometry of the double bond [Eq. (37] and Table 6]. 

Reactions of allyl ethers with RLi can lead to replacement of the alkoxy group ", as shown by allyl methyl ether ° ... 

However, Narayanan and Iyer found that cleavage can be effected with boron trifluoride and acetic anhydride alone and that a lithium halide slows down the reaction and does not decrease elimination to the olefin. They obtained cholesteryl acetate from cholesteryl methyl ether (homoallylic) in 93% yield (15 hrs, at 0°). Cleavage of an allylic methyl ether (A -cholestene-3y3-ol methyl ether) required only 3 min. at —18° (90% yield) under less mild conditions the main product was the A Miene. Cleavage of saturated ethers was attended with considerable elimination. R. D. Youssefyeh and Y. Mazur, Tetrahedron Letters, 1287 (1962)... 

Allyl methyl ether (ethyl diazoacetate, rhodium catalysis) and allyl terf-butyl ether (dimethyl diazomalonate, copper catalysis) yield cyclopropanes exclusively. With y-substituted allyl methyl ethers, C-0 insertion is generally strongly favored over cyclopropanation, even with tetraacetatodirhodium as catalyst.In view of these findings, the cyclopropanation of ( )- ,4-dibenzyloxybut-2-ene in moderate yield, only, to give (la,2a,3j5)-31 is notable. 

Structure CXXXVTI is compatible with several miscellaneous reactions and properties of tazettine. It accounts for the production of phenanthridine derivatives by zinc dust distillation (128a) and Oppen-auer oxidation (55) more satisfactorily than CXXXII. The double bond of tazettine is sufficiently removed from the nitrogen atom to have no effect on the basicity of the alkaloid. The allylic methyl ether may be cleaved with hydrochloric acid to a mixture of two epimeric allylic alcohols, tazettinol (CLI) and isotazettinol (CLII). Methylation of tazettinol afforded 0-methyltazettine methiodide, identical with that obtained by the methylation of tazettine. Under similar conditions, isotazettinol afforded the epimeric 0-methylisotazettine methiodide. Both methiodides gave 2-(4-methoxyphenyl)-4,5-methylenedioxyben-... 

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