Trimethyl Ethers

The structure of compound A was established in part by converting it to known compounds Treat ment of A with excess methyl iodide in the presence of silver oxide followed by hydrolysis with dilute hydrochlonc acid gave a tnmethyl ether of D galactose Companng this trimethyl ether with known trimethyl ethers of D galactose allowed the structure of compound A to be deduced... 

Many patents have been issued on the use of pyrogaUol derivatives as pharmaceuticals. PyrogaUol has been used extemaUy in the form of an ointment or a solution in the treatment of skin diseases, eg, psoriasis, ringworm, and lupus erythematosus. GaUamine triethiodide (16) is an important muscle relaxant in surgery it also is used in convulsive-shock therapy. Trimethoprim (2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine) is an antimicrobial and is a component of Bactrin and Septra. Trimetazidine (l(2,3,4-trimethoxybenzyl)piperazine (Vastarel, Yosimilon) is used as a coronary vasodilator. l,2,3,4-Tetrahydro-6-methoxy-l-(3,4,5-trimethoxyphenyl)-9JT-pyrido[3,4- ]indole hydrochloride is useful as a tranquilizer (52) (see Hypnotics, sedatives, ANTICONVULSANTS, AND ANXIOLYTICS). Substituted indanones made from pyrogaUol trimethyl ether depress the central nervous system (CNS) (53). Tyrosine-and glycine(2,3,4-trihydroxybenzyl)hydrazides are characterized by antidepressant and anti-Parkinson activity (54). 

The alkaloid reserpiae [50-55-5] which is isolated from the roots of Kauwoljia serpentina T., contains a gaUate trimethyl ether moiety. Reserpiae is used as an antihypertensive and a tranquilizer. A vinylogue of reserpiae, rescinnamine [24815-24-5] is also an antihypersensitive (75). Methoxsalen [298-81-7] (8-methoxypsoralen 7JT-9-methoxy-furo [3,2- ] [l]benzopyran-7-one) (21), a furocoumatia that occurs ia plants, eg, l eguminosae and Umbelliferae is used ia the treatment of vitiligo, as a suntanning promoter, and as a sunburn protectant. It is also available by synthesis (76). 

Colchiciae (23) is a toxic substance occurring ia Colchicum autumnale, it coataias the aucleus of pyrogaUol trimethyl ether. Colchiciae has beea used ia the treatmeat of acute gout, and ia plant genetics research to effect doubling of chromosomes. 

The reaction of 1,3,5-tribromobenzene with excess sodium methoxide in methanol—/V,/V-dimethy1formamide and in the presence of a catalytic amount of cuprous iodide gives ca 90% yield phlorogluciaol trimethyl ether (1,3,5-trimethoxybenzene). The latter is hydrolyzed with 35 wt % hydrochloric acid at room temperature to give a 90% yield of phlorogluciaol (140—142). 

Derivatives. Oxidation of pyrogaHol trimethyl ether with nitric acid, followed by reduction ia acetic anhydride and treatment of the product with aluminum chloride, affords 3,6-dihydroxy-2,4-dimethoxyacetophenone (228). 3,4,5-Trimethoxyphenol (antiarol) has been prepared by treatment of... 

How many trimethyl ethers of D-galactose are there Which one is the same as the product derived from compound A ... 

Asarone, or 4-propenyl-l. 2.5. trimethoxybenzene, Cj Hj Og, is the trimethyl ether of a triphenol, which is found occurring naturally in the essential oil of Asarum arifolium, and to a small extent in matico and acorus oils. It is an aromatic crystalline compound having the following characters —... 

This protocol could be extended to a range of different ,/i-unsaturated carbonyl compounds and either activated or deactivated aryl iodides [22], An application of related Heck chemistry to the synthesis of methylated resveratrol (3,4, 5-trihydroxy-( )-stilbene) is shown in Scheme 6.4 [23]. The phytoalexin resveratrol exhibits a variety of interesting biological and therapeutic properties, among them activity against several human cancer cell lines. Botella and Najera have shown that the trimethyl ether of resveratrol (Scheme 6.4) can be rapidly prepared by microwave-assisted Heck reaction of the appropriate aryl iodide and styrene derivatives, using the same oxime-derived palladacycle as indicated in Scheme 6.3. 

Scheme 6.4 Synthesis of resveratrol trimethyl ether via Heck arylation.

In 1997, Steglich reported (Scheme 7) the synthesis [29] of lamellarin G trimethyl ether (36) based on the biosynthetic proposal that such compounds arise from 3,4-dihydroxyphenylalanine (DOPA) secondary metabolites. 

Ruchirawat has also been active in the construction of the lamellarins and his route [33] to lamellarin G trimethyl ether (36) is depicted in Scheme 11. 

In this route a dihydroisoquinoline (58) is N alkylated with a highly functionalized o -bromoacetophenone (59) to give a quaternary salt (60), which is treated with base and cyclizes to a pyrroloisoquinoline (60). The pyrrole nucleus is then formylated under Vilsmeier-Haack conditions at position 5 and a proximate mesylated phenolic group is deprotected with base to yield a pen-tasubstituted pyrrole (61). Subsequent oxidative cyclization of this formylpyr-role produces the 5-lactone portion of lamellarin G trimethyl ether (36). This sequence allows for rapid and efficient analog synthesis as well as the synthesis of the natural product. 

Ishibashi and Iwao have reported [37] a novel route (Scheme 13) to lamellarin G trimethyl ether that utilizes a much different strategy than the one outlined in Scheme 8. The synthesis begins with the dialkylation of a phenethyl amine with ethyl a-bromoacetate to yield an aminodiester (67). 

Handy and coworkers [38] have also offered a very useful approach (Scheme 14) to lamellarin G trimethyl ether (36) and they have referred to this strategy as being modular in nature . The route starts with an N-protected 4-bromo-2-carboethoxypyrrole (72) and involves introduction of three different aryl groups via three sequential, regiospecific halogenations, which are... 

Adsorption of a specific probe molecule on a catalyst induces changes in the vibrational spectra of surface groups and the adsorbed molecules used to characterize the nature and strength of the basic sites. The analysis of IR spectra of surface species formed by adsorption of probe molecules (e.g., CO, CO2, SO2, pyrrole, chloroform, acetonitrile, alcohols, thiols, boric acid trimethyl ether, acetylenes, ammonia, and pyridine) was reviewed critically by Lavalley (50), who concluded that there is no universally suitable probe molecule for the characterization of basic sites. This limitation results because most of the probe molecules interact with surface sites to form strongly bound complexes, which can cause irreversible changes of the surface. In this section, we review work with some of the probe molecules that are commonly used for characterizing alkaline earth metal oxides. 

Cellulose trimethyl ether Chloroform, toluene Ethanol, diethyl ether, petroleum ether... 

Xylosyl(l — 2)glucoside 6-Neohesperidoside Scutellarein 6,7,4 -trimethyl ether (salvigenin) Gelonium multiflorum seeds Euphorbiaceae 76... 

Luteolin 5,3, 4 -trimethyl ether 7-Xylosyl(l — 6)glucoside 7-Rutinoside... 

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