Formation of Naphthols from Benzenoid Compounds and Alkynes

7 Formation of naphthols from benzenoid compounds and alkynes 

2-Aryl dialdehydes were reacted with symmetrical dialkylacetylenes in the presence of a niobium(lll) catalyst to afford 2, dialkyl-1-naphthols in high yield. With unsymmetrical acetylenes, the formation of two products is highly dependent upon the structure of the alkyl groups (ref.77). 

In the case of 1-dodecyne, reaction with the same dialdehyde in the presence of niobium(V)chloride led to a variety of products, including 2-n-decylnaphthalene (23%), a minor proportion of 2-n-decyl-1-naphthol (14%), 2-n-decylnaphthalene-1,4-diol (2%) and 1-n-dodecene (ref.78). 

The diazoketone shown upon irradiation, or thermal treatment, afforded a 2-naphthol derivative through intermediate formation of an arylketen (ref.79). By contrast, 

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