Methoxyl groups method

Corypalline, CnHijOjN (Corydalis spp. Nos. 9, 22 list, p. 170). This phenolic base, m.p. 168°, picrate, m.p. 178°, contains one methoxyl group and on methylation yields 2-methyl-6 7-dimethoxytetrahydrof5oquinoline, Ci2Hi,02N, m.p. 82°, and on ethylation, 2-methyl-6-methoxy-7-ethoxy-tetrahydrofsoquinoline, m.p. 65°, whence the free hydroxyl appears to be at C and this has been confirmed by the synthesis of corypalline by a method analogous with that used by Spath, Orekhov and Kuffner. Corypalline is therefore hydrohydrastinine (XII) with the methylenedioxy group replaced by MeO at C and. OH at C (Manske). ... 

The ease with which one methoxyl group is lost in this reduction was at first explained by assuming carbon atom 5 as its point of attachment, but in the following year the same authors prepared by Pschorr s method 3 4 6 7-tetramethoxyphenanthrene, colourless prisms, m.p. 124-5°, which proved to be identical with Goto s dimethylsinomenol, and on this... 

Worenine. This alkaloid, also obtained by Kitasato from Coptis japonica was isolated as the tetrahydro-base, C,oHjg04N, which crystallises from alcohol in colourless prisms, m.p. 212-3°, and is oxidised by iodine in alcohol to worenine iodide, yellow crystals from which worenine chloride, thin orange-yellow prisms, m.p. 295° (dec.), can be obtained. Tetrahydro-worenine behaves as a tertiary base, contains methylenedioxy- but no methoxyl groups, and its absorption spectrum closely resembles that of tetrahydrocoptisine from which it differs in empirical composition by. CHj. Worenine is, therefore, represented by (XXX), the alternative position (a) for the methyl group being untenable, since a-methyltetra-hydrocoptisine obtained by Freund s method is not identical with... 

The 2,3,7,8,10-pentaoxygenated benzo[c]phenanthridine alkaloid san-guilutine (248) was also conveniently synthesized according to the above method (Scheme 43) (138). The presence of the methoxyl group at C-5 peri to the cyclization position (C-4) was at first anticipated to retard cyclization however, the cyclization of the acetal 246 proceeded smoothly to give oxysanguilutine (247) in high yield. 

For maximum efficiency, methylation should be a single-phase reaction and so those methods employing aqueous alkali are most suitable for water-soluble compounds and the Purdie method for non-polar compounds. A carbohydrate which is initially soluble in water e.g., starch, dextran) may be less soluble when partially methylated and for this reason an inert solvent e.g., acetone, dioxane, carbon tetrachloride) is often introduced during the later stages of a methylation with dimethyl sulfate. It is interesting to note that methyl a-D-glucopyranoside forms a trithallium derivative which is insoluble in water and consequently the introduction of more than three methoxyl groups by the Menzies method... 

Another method of synthesis of derivatives of 3-methyl-D-glucose lies in the scission of the anhydro-ring of 2,3-anhydro-D-allose derivatives with sodium methoxide, when the entry of the methoxyl group is accompanied by a Walden inversion on C3.82... 

Methylated phenols very often form part of the molecule of natural products, in particular, of alkaloids. In the elucidation of their constitution the quantitative determination of the methoxyl groups is of great importance. This determination is carried out by the excellent method of Zeisel, in which the methyl group is removed as methyl iodide by the action of concentrated hydriodic acid. This method (directions, p. 80) should be practised with the anisole already prepared. 

Numerous derivatives of (1) have been thus prepared, notably 2,3-dimethyl (or dialkyl)benzofurans Bz-substituted by alkyl radicals,36,213-218 methoxyl groups,101,219-221 halogen atoms,217,222-224 aryl groups,225 acetyl groups,215,218,226 formyl groups,222,226 and carboxyl groups.226,227 The method is especially valuable in the case of formyl derivatives, which are difficult to obtain otherwise. 

Several methyl ethers of the above dideoxy sugars have been synthesized,2 essentially by the above methods, with introduction of a methoxyl group (usually i t C-3) at a convenient stage of the synthesis. 

Cumming s Modification.—(J. S. 0.1., 41, 20.)—A convenient apparatus for the estimation of methoxyl groups by the Zeisel method consists of a long-necked round-bottomed flask attached by a ground-glass joint to a bulbed U-tube. The methyl iodide generated by the interaction of hydriodic acid and the methoxyl group is absorbed in alcoholic silver nitrate. Pyridine may also be used as absorbent. (J. C. S., 117, 193.) For purification of hydriodic acid, see p. 506. 

All alkaloids of the group have methoxyl groups at C-17 and C-21 and the same skeleton. The structure of these alkaloids was established by a combination of chemical and spectral methods. 

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