1 -Acetyl-3,4-dihydronaphthalene

Catalytic systems at very low metal loading 0.1% (w/w) obtained in this way can be conveniently used in the hydrogenation of a,P-unsaturated ketones to the corresponding saturated carbonyl compounds with very high efficiencies and selectivities. In Table 4 we report the results obtained in the selective hydrogenation of 4-(6-methoxy-2-naphthyl)-3-buten-2-one, 1, and 2-acetyl-5,8-dimethoxy-3,4-dihydronaphthalene, 2, to the corresponding saturated carbonyl products (I), which are important intermediates... 

The behavior of Diels-Alder adducts substituted at the C(3) position (313) is different because the substituent has to prevent an aromatization. Treatment of triketone 313 with pyridine-methanol (1 1, v/v) at 22 °C results in the expected [l,5]-acetyl shift and gives a good yield of the triketone 314, which isomerizes smoothly when heated in the same medium at 65 °C to furnish dihydronaphthalene 315 (equation 109)168. Similar treatment of the triketone 316 affords the bicyclic product 318 rather than 319, presumably via the intermediate 317 (equation 110)168. 

Co-ozonolysis of 1,2-dihydronaphthalene with formaldehyde, acetyl cyanide (pyruvonitrile), benzoyl cyanide, or acetaldehyde afforded an ozonide attached to a benzaldehyde group 89 and none of the isomeric ozonide with a propionaldehyde group. This indicates the preference for scission of the molozonide so as to favor conjugation between the aromatic ring and the aldehyde group rather than with the carbonyl oxide group. Subsequent co-ozonolysis of products 89 with vinyl acetate produced diozonides 90, as shown in Scheme 26 and Table 11. 

In a useful approach to partially reduced benzotf]quinoline-l-ones, 1-tetralone is converted into l-acetyl-3,4-dihydronaphthalene which undergoes a Mannich reaction in acetic acid to yield the benzoquinolinone directly (J.J. Salley, Jr. and R. A. Glennon, J. heterocyclic Chem., 1982, 19, 545). 

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