Isolation of keto-s-phenylthioxime of [23]cyclophane-1,2-dione. Re-visited contraction of 1,2,5-thiadiazole ring incorporated in a [23]cyclophane bridge by phenylmagnesium bromide

2³]Paracyclophane derivative 3 of keto-S-phenylthioxime which is the hydrolyzed product of the hypothetical intermediate in the reaction of 1,2,5-thiadiazole with organometallic reagents, was obtained, together with diketone 1 , in the reaction of 1,2,5-thiadiazolo2³]paracyclophane 2 with two equivalents of phenylmagnesium bromide. Contrary, 2³]metacyclophane 7 gave only diketone 12 in the reaction with phenylmagnesium bromide under the same conditions.