Methoxy-1-tetralones

Methoxypropene, 328-329 6-Mcthoxy-1,2,3,4-tetrahy dronaphthalene-1 -carboxylic acid, 148 6-Methoxy-1 -tetralone, 148 Methoxythioanisoles, 473 a-Methoxy-a-trifluoromethylphenylacetic acid, 330... 

In Stork s synthesis (148), 5 - methyl - 6 - methoxy - 1 - tetralone (CLXXXIV) was converted into the tricyclic intermediate CLXX XVII in several steps involving condensation with dimethyl carbonate, addition of methyl isopropenylketone, and cyclization to the a, -unsaturated ketone CLXXXVI, followed by catalytic hydrogenation, replacement of the hydroxyl group in the resulting dihydro alcohol by a chlorine atom on treatment with phosphorus oxychloride in pyridine solution, and elimination of hydrogen chloride by methanolic sodium methoxide. 

The first total synthesis of (+)-brasiliquinone B was accomplished by V.H. Deshpande and co-workers starting from 7-methoxy-1-tetralone. The key step of their synthesis was the Friedel-Crafts alkylation of 2-ethyl-7-methoxytetralin with 3-bromo-4-methoxyphthalide in the presence of tin tetrachloride. 

An alternative approach to the tetracyclic systan forms the heterocyclic ring by nucleophilic addition of an amine to a carbonyl group. Application of the Friedlander quinoline synthesis to various methoxy-1-tetralones yields the methoxy-5,6-dihydrobenz-[c]acridines, which are dehydrogenated to the aromatic compound by distillation from palladium-charcoal (M. Croisy-Delcey et al. J. med. Chem., 1983, 26, 303). 

Ozonisation of 2-furfurylidene-6-methoxy-1-tetralone in ethyl acetete at -78°C, removal of excess ozone with nitrogen and treatment of the ozonide in glacial acetic acid with 30% hydrogen peroxide, afforded after 12 hours,... 

Another synthetic route starts from theenol ether (57) the preparation of which from 6-methoxy-1-tetralone has been described in Scheme 40, When this ether was all lated with m-methoxyphenethyl bromide, the product of angular alkylation (62) was formed in predominating amount, with a small amount of the tetracyclic compound (61) as a by-product. Alkylation products were formed in a different ratio from the enol ether (60) in this case the methoxyketone (61) predominated somewhat [870, 889]. 

The synthesis of the initial compound (277) can be effected in three ways (Scheme 106). The first of them consists in the reduction with alkali metals and alcohol of 2,6-dimethoxynaphthalene (280) [79, 950, 951]. The second method starts from 6-methoxytetralin (275) which, on treatment with lead tetraacetate, gives the acetate (276) which forms compound (274) when acetic acid is split out oxidation of the latter with perbenzoic acid and pyrolysis leads to the desired product (277) [952, 953]. The most suitable method for large amounts proved to be the third method, starting from 6-methoxy-1-tetralone (272), the synthesis of which has been described in Chapter II (Scheme 1). The tosylhydrazone (273) obtained from it, on being heated with sodium glycolate and subsequently distilled in vacuum over potassium bisulfate gives the tetraene (274), which, on oxidation with peracetic acid and treatment of the reaction product with hydrochloric acid forms the ketone (277) [954]. 

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