Reaction of 1-(methylsulfonyl)4-phenylphthalazine (I) and active methylene compounds was carried out in benzene, in the presence of sodium amide. As the so-called active methylene compounds, ethyl cyanoacetate (IIIa), ethyl acetoacetate (IIIb), ethyl malonate (IIIc), malononitrile (IIId), and phenylacetonitrile (IIIe) were used. In addition, reaction was also examined with ethynylbenzene (IIIf), acetonitrile (IIIg), 2-picoline (IIIh), and ethyl acetate (IIIi). As would be expected, reaction with IIIa to IIIf respectively afforded ethyl a-cyano-4-phenyl-1-phthalazineacetate (IVa), ethyl α-acetyl-4-phenyl-1-phthalazineacetate (IVb), ethyl 4 -phenyl-1-phthalazinemalonate (IVc), 4-phenyl-1-phthalazinemalononitrile (lVd), α, 4-diphenyl-1-phthalazineacetonitrile (IVe), and 1-phenyl-4-(phenylethynyl)phthalazine (IVf) (Chart 1 and Table I). From the reaction witln IIIg, a compound considered to have been formed by the reaction of the product corresponding to the above type, 4-phenyl-1-phthalazineacetonitrile (IVg), with I was obtained in the forms of bis(4-phenyl-1-phthalazinyl)acetonitrile (IVg') (Chart 2 and Table I). In the case of IIIh, this compound did not take part in the reaction, and the reaction of I and sodium amide took place to form 1, 1'-imino-bis[4-phenylphthalazine] (VI). Reaction of I with IIIi afforded 1-ethoxy-4-phenylphthalazine (VII) (Chart 2). Hydrolysis of IVg' gave 1, 1'-methy1enebis[4-phenylphthalazine](VIII) (Chart 3). In a previous paper,
1) the by-product formed by the reaction of I and methyl ketone in the presence of sodium amide was assumed as 4, 4'-diphenyl-1, 1'-biphthalazine but this assumption was found to be wrong, and the product is now corrected to VIII. The route of its formation is presumed as shown in Chart 4.
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