Ethers, methyl allylic

Cleavage of dialkyl ethers. Methyl, allyl, and benzyl alkyl ethers are cleaved by this combination to the alcohols and methyl, allyl, and benzyl iodide (75-90% yield). The reagent also cleaves epoxides to rran5-2-iodoalkanols (—70% yield). 

The 7, i5-unsaturated alcohol 99 is cyclized to 2-vinyl-5-phenyltetrahydro-furan (100) by exo cyclization in aqueous alcohol[124]. On the other hand, the dihydropyran 101 is formed by endo cyclization from a 7, (5-unsaturated alcohol substituted by two methyl groups at the i5-position. The direction of elimination of /3-hydrogen to give either enol ethers or allylic ethers can be controlled by using DMSO as a solvent and utilized in the synthesis of the tetronomycin precursor 102[125], The oxidation of the optically active 3-alkene-l,2-diol 103 affords the 2,5-dihydrofuran 104 in high ee. It should be noted that /3-OH is eliminated rather than /3-H at the end of the reac-tion[126]. 

Eugenol methyl ether (4-allyl-l,2-dimethoxybenzene) [93-15-2] M 178.2, m -4 , b 127-129 /llmm, 146 /30mm, 154.7 /760mm, dj 1.0354, n 11.53411. Recrystd from hexane at low temp and redistd (preferably in vacuo). [Hillmer and Schoming Z Phys Chem [A] 167 407 1934 Briner and Fliszdr Helv Chim Acta 42 2063 1959.]... 

Me2BBr, CICH2CH2CI, 0°-rt, 70-93% yield." The reagent also cleaves phenolic methyl ethers tertiary ethers and allylic ethers give the bromide rather than the alcohol. 

Allenyl Silyl enol ethers, 86 Allyl alcohol trimethylsilyl ether, 84 Allyl carbonates, 114-15 9 Allyl-ay 2 octalone, 34-5 2-Allyl-2 methylcyclohexanone, 106 (Allyldimethylsilyl)methyl chloride, 58, 59 (AUyldimethylsilyl)methylmagnesium chloride, 59... 

Diethyl ether, methyl n-propyl ether, diethylamine, N-methyl-1 -propanamine, acetone, allyl alcohol, dimethylformamide, propanamide, 2-methylpropan-amide, 2,2-dimethylpropanamide, benzamide, dichloromethane, toluene, ethyl N-acetyl-glycinate, -alaninate, -methioninate, and -aspartate, ethyl acetate, tetrahydrofuran... 

In carbohydrate chemistry, the preparation of ethers that are stable in the presence of acids, bases, and aqueous alkali is an important analytical and synthetic tool. The methods used for the etherification of hydroxyl groups51 generally employ reactions of unprotected sugars and glycosides with methyl, allyl, benzyl, triphenylmethyl, and alkylsilyl halides in the presence of a variety of aqueous and nonaqueous bases. 

A. J. Colussi, F. Zabel, and S. W. Benson, Very low-pressure pyrolysis of phenyl ediyl ether, phenyl allyl ether, and benzyl methyl-edier and endialpy of formation of phenoxy radical,/ t. J. Chem. 

Bowen, R.D. Wright, A.D. Derrick, P.J. Unimolecular Reactions of Ionized Methyl Allyl Ether. Org. Mass Spectrom. 1992, 27,905-915. 

Reductive coupling of alkenes and l -dienes. In the presence of Hg(OAc), or Hg(OAc), HgO (I 1) and NaBH(OCH,), 1,3-dienes undergo reductive coupling in methanol with alkenes substituted with election-withdrawing groups (CN, CCXX H, ( C)C ll 1) to form the methyl ether of allyl alcohols. ... 

When 32 is photolyzed in the presence of methyl allyl ether (62),50 51 the generated silylene 13 initially coordinates to the ether oxygen to give 63, w ich subsequently rearranges to allylsilane 64 (Scheme 17), a reaction... 

Reduction of derivatives of ally lie alcohols. Nickel boride can effect reduction of allylic alcohols to alkenes, but yields are generally improved by reduction of the acetates, benzoates, or trifluoroacetates.1 Reduction of allylic benzyl ethers to alkenes is effected in higher yield with Raney nickel. Methyl ethers are not reduced by either reagent. The trimethylsilyl ethers of allylic alcohols are reduced to alkenes by nickel boride in diglyme.2... 

The bromocyclization of A/,jV-dialkylaminomethyl ethers of allyl and propargyl alcohols to form oxa-zolidinium salts has been reported, but not used in synthesis.255 The heterocyclization of /V-acylamino-methyl ethers with mercury salts has been used for stereoselective synthesis of a variety of 1,2-amino alcohol systems. These cyclizations form rans-4,5-dialkyl oxazolidine products with good to excellent stereoselectivities (equation 120 and Table 33). As shown by entry 5, 6-endo cyclization predominates (6 3) with an internal double bond of ( )-configuration, but this mode of cyclization is reduced with substrates containing a (Z) double bond and/or allylic oxygen substitution (Table 33, entries 6-9). 

The preparation of alkyl methyl ethers may be readily effected under PTC conditions from the alcohol, dimethyl sulphate and 50 per cent w/w aqueous sodium hydroxide, employing tetrabutylammonium hydrogen sulphate as catalyst.95 The usefulness of this procedure has been extended, and optimum conditions have been described for the alkylation of a range of aliphatic alcohols using, for example, 1-chlorobutane or benzyl chloride.96 The PTC preparative examples described in Expt 5.73 are for the methylation, allylation, but-2-enylation and benzylation of, for example, 2-hydroxymethyl-l,4-dioxaspiro[4.5]decane (Expt 5.63), and have been developed in the editors laboratories. These methods have also been applied to the alkylation of protected monosaccharide derivatives (p. 652). 

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 structure of XXVI was deduced from the fact that it was different from the 2-cinnamylphenol obtained by direct C-cinnamylation of phenol.16 Later investigators showed that XXVI is the sole product ozonization yielded formaldehyde but not benzaldehyde. 7-Methyl-allyl phenyl ether also rearranges with inversion, yielding 2-(a-methyl-allyl)-phenol 36 the structure of the rearrangement product has been definitely established87 38 by a combination of degradative and synthetic procedures. 

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). 

Deprotection of MEM and MOM ethers. Methoxyethoxymethyl and methoxy-methyl ethers are cleaved to the alcohol by this reagent in high yields. Either 2-butanone or 2-methyl-2-propanol is recommended as solvent. The procedure is particularly useful for cleavage of ethers of allylic alcohols, for which ZnBr, and TiCh are not useful. 

Berim, A., Schneider, B. and Petersen, M. (2007) Methyl allyl ether formation in plants novel S-adenosyl L-methionine coniferyl alcohol 9-O-methyltransferase from suspension cultures of three Linum species. Plant Mol. Biol, 64, 279-91. 

SYNS 5-ALLYL-1.3-BENZODIOXOLE ALLYL-CATECHOL METHYLENE ETHER ALLYLDIOXY-BENZENE METHYLENE ETHER l-ALLYL-3,4-METHYT.ENEniOXYBENZENE 4-AIl,YL-l,2-METHYI.ENEDIOXYBENZENE m-ALLYLPYRO-CATECHIN METHYLENE ETHER 4-ALLYI.PYRO-CATECHOL FORMALDEHYDE ACETAL ALLYL-PYROCATECHOL METHYLENE ETHER 1,2-METHYL-ENEDIOXY-4-ALLYLBENZENE 3,4-METHYL-ENEDIOXY-ALLYLBENZENE 5-(2-PROPENYL)-l,3-BENZODIOXOLE RCA WASTE NUMBER U203 RHYUNO OIL SAFROLE SAFROLE MF SHIKIMOLE SHIKOMOL... 

The a-substituted 1-methyl allyl vinyl ether was shown to isomerize with a strong preference for the irons product (i.e., 95 % irons, 5 % cfe) . This corresponds to a conformational preference for equatorial methyl (as opposed to axial) in the chair transition state of about 2.4 kcal.mole . The identical value was calculated from the irons product preference in the allyl ester Claisen rearrangements (see a-methyl allyl acetate and a-trifluoromethyl allyl trifluoroacetate). 

The results are shown in Table 23. Relative rate data were obtained by simultaneous pyrolysis of pairs of ethers. Since the total rate spread of all ethers from the slowest (ethyl allyl) to the fastest (diphenylmethyl-1-methyl allyl) was only a factor of 40, it is apparent that substituent effects are relatively very small (see ester and vinyl ether eliminations). Polarization in the transition states must, therefore, be minimal. Cookson and Wallis ° noted the following rate trends ... 

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