2-Aryliden-l-tetralones

The fixed geometry of a, 3-unsaturated ketones in the S-cis form, as observed in arylidene alkanones, influences their reactivity. For example, the reaction of arylhydrazines with 3,5-diarylidene-4-piperidones, 2-arylidene-l-tetralones, 2,6-diarylidenecyclohexanones and 2-arylideneindan-l,3-diones requires stronger conditions than for the case of their noncyclic analogues [76, 77, 78, 79, 80, 81, 82, 83, 84]. However, arylidene derivatives of cyclohexanone, 1-indanone, 4-chromanone, 4-thiochromanone and TV-methyl-4-piperidone hydrochloride react with hydrazines more easily [85,86,87,88], It is interesting to note that the more complicated and sterically hindered unsaturated ketones of the spiro type 64 react with hydrazine and phenylhydrazine very easily in the presence of piperidine, leading to pyrazoles 65 in high yields [89] (Scheme 2.16). 

The ketene 0,0-acetals 83 were prepared from the corresponding bromo derivatives by reaction with strong base A diastereoselective synthesis of the trans- and cis 84 was carried out. Condensation of substituted aminothiophenols and 2-arylidene-l-tetralone afforded 1,4-thiazepines 85. Condensation of o-phenylenediamines with P-ketoesters or 1,1,1-trifluoromethyl-3-(isobutoxymethylene)-2-propanones gave 84. ... 

Aminonaphtho[l,2-b]pyrans are converted into 5,6-dihydrobenzo[h]quinolines under basic conditions through a Dimroth rearrangement. The oxygen heterocycle is formed by a Michael addition of malononitrile to a 2-arylidene-l-tetralone and the whole sequence provides an... 

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