Methyl ethers structure

Chemical Name 3-methoxy-19-nor-17a-pregna-1,3,5( 10)-trien-20-yn-17-ol Common Name 17a-ethynylestradiol 3-methyl ether Structural Formula ... 

Chemical Name 2,2-dichloro-1,1-difluoro-1-methoxyethane Common Name 1,1-difluoro-2,2-dichloroethyl methyl ether Structural Formula GHjOCF CHCI ... 

Chemical Name 10-methoxy-1,6-dimethylergoline-8(3-methanol 5-bromonicotinate (ester) Common Name Nicotergoline 1-methyllumilysergol-8-(5-bromonicotinate) 10-methyl ether Structural Formula ... 

C4H9NO) (c4h90)+ Propionaldoxime-0-methyl ether Structure of decomposing ions assumed to be 25 g, 1 279... 

Poly(methoxymethylstyrene) and co-polymers from (2,2-disubstituted 1,.5-dioxolan-4-yl)methoxymethylstyrene crosslink readily under u.v. light (Scheme 17). Here both the 1,3-dioxolane and benzyl methyl ether structures participate in the crosslinking. o-Nitrobenzyl cholate esters have been used as effective photosensitizers in resists," as have poly-(N-vinylamine) and methacrylate co-polymers with substituted cinnamic or cinnamylidene groups. 

A number of sub-fractions have been isolated from the hemicellulose B fraction of the husks of Sorghum grain. Three of these sub-fractions were each found to contain residues of L-arabinose, D-xylose, D-galactose, D-glucose, and D-glucuronic acid and its 4-0-methyl ether. Structural studies confirmed that the three polysaccharides were xylans with the usual )8-l,4-linked main chain. There were considerable differences in the D.P. of these polysaccharides, the values obtained being 993, 2380, and 851. 

These results justified the nuclear structures (I) and (II) assigned to bebeerine methyl ether and its nitrogen-free degradation product respec-... 

The alkynylation of estrone methyl ether with the lithium, sodium and potassium derivatives of propargyl alcohol, 3-butyn-l-ol, and propargyl aldehyde diethyl acetal in pyridine and dioxane has been studied by Miller. Every combination of alkali metal and alkyne tried, but one, gives the 17a-alkylated products (65a), (65c) and (65d). The exception is alkynylation with the potassium derivative of propargyl aldehyde diethyl acetal in pyridine at room temperature, which produces a mixture of epimeric 17-(3, 3 -diethoxy-T-propynyl) derivatives. The rate of alkynylation of estrone methyl ether depends on the structure of the alkyne and proceeds in the order propar-gylaldehyde diethyl acetal > 3-butyn-l-ol > propargyl alcohol. The reactivity of the alkali metal salts is in the order potassium > sodium > lithium. 

This method is probably the most commonly used one for the cleavage of methyl ethers, because it generally gives excellent yields with a variety of structural types. The solid complex BBr3-Me2S that is more easily handled can also be used. BBr3 will cleave ketals. 

The infrared spectrum of 2-hydroxythiophene was originally interpreted as showing both vOH and vC=0 peaks indicating that it exists as a mixture of the hydroxy form 39 (R — H) and at least one of the 0X0 forms, 40 and/or 41. The ultraviolet spectrum of 2-hydroxythiophene is different from that of the corresponding methyl ether (39, R = Me) suggesting the presence of the chromophore contained in structure 40. The facts that this compound gives a positive... 

UV spectra of a variety of 1 -alkyl-1 //-1-benzazepines,20,21 3//-l-benzazepines,20 l-acyl-l//-l-benzazepines,1 3,22,23 3-acyl-3//-3-benzazepines,22-23 3-alkyl-37/-3-benzazepines and their cations in concentrated sulfuric acid,24,25 and 3-mesyl-3//-3-bcnzazepine,2ft have been recorded. A comparison of the UV spectra of 3-alkyl-l, 5-dihydroxy-3//-3-benzazepinc-2,4-dicarboxylates and their bis-O-methyl ethers supports an enol rather than an amide structure for these derivatives.14... 

In 1947, L-rhamnose was first recognized by Stacey as a constituent of Pneumococcus Type II specific polysaccharide. This finding was confirmed, in 1952, by Kabat et al. and in 1955 again by Stacey when 2,4- and 2,5-di-O-methyl-L-rhamnose were synthesized and the former was shown to be identical with a di-O-methylrhamnose, obtained by hydrolysis of the methylated polysaccharide. This result indicated a pyranose ring structure for the rhamnose units in the polysaccharide. Announcement of the identification of D-arabinofuranose as a constituent of a polysaccharide from M. tuberculosis aroused considerable interest. The L-enantiomer had been found extensively in polysaccharides, but reports of the natural occurrence of D-arabinose had been comparatively rare. To have available reference compounds for comparison with degradation products of polysaccharides, syntheses of derivatives (particularly methyl ethers) of both d- and L-arabinose were reported in 1947. 

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