Hydroxy aldehydes naphthalenes

The interaction of peri-acyloxybromo ketones Til with aromatic aldehydes in the presence of sodium methylate gives rise to 2-arylmethy-lidene derivatives of naphtho[bc]pyran-3-one 274 (89TH1). In all reactions just described, the pyran ring-closure occurs by formation of a C—O bond between the /3-carbon atom of a substituent in position 1 of the naphthalene nucleus and the oxygen atom of an 8-hydroxy group. 

In basic chemicals, nitrile hydratase and nitrilases have been most successful. Acrylamide from acrylonitrile is now a 30 000 tpy process. In a product tree starting from the addition of HCN to butadiene, nicotinamide (from 3-cyanopyridine, for animal feed), 5-cyanovaleramide (from adiponitrile, for herbicide precursor), and 4-cyanopentanoic acid (from 2-methylglutaronitrile, for l,5-dimethyl-2-piperidone solvent) have been developed. Both the enantioselective addition of HCN to aldehydes with oxynitrilase and the dihydroxylation of substituted benzenes with toluene (or naphthalene) dioxygenase, which are far superior to chemical routes, open up pathways to amino and hydroxy acids, amino alcohols, and diamines in the first case and alkaloids, prostaglandins, and carbohydrate derivatives in the second case. 

Enaminones react with 2-hydroxybenzaldehydes on prolonged heating under Dean and Stark conditions to give chromenes. / m -cyclization of aldehyde and hydroxy groups by reaction with ethyl chloroacetate in an alkaline medium produces a pyrano derivative in high yield. T erf-annulated naphthalenes and similar compounds are discussed in a review [390S]. 

The same reaction is observed between /ran5-l-hydroxy-2-hydroperoxy-l,2,3,4-tetrahydro-naphthalene and aldehydes or ketones in the presence of catalytic amounts of Amberlyst-15 or trimethylsilyl trifluoromethanesulfonate the rranj-fused trioxanes being formed in 75-95% yield <92C114>. 

By contrast with the conditions for aldehydes, ketones have been oxidised to phenols by methodology essentially that of the cumene-hydroperoxide rearrangement. In the naphthalenic series, treatment of the derived t-alcohol shown with excess 90% hydrogen peroxide followed by stirring of the mixture with a little 4-toluenesulphonic acid for 6 hours at 22 C gave the phenolic product, 2-hydroxy-3-methoxy-5,6,7,8-tetrahydronaphthalene in 85% yield (ref.45). 

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