The closure of rings through the m-and p-positions of the benzene nucleus is one of the conventional problems of organic chemistry that long resisted solution. As soon as a rational theory of ring closure had been developed, 2 it became apparent that success might easily be achieved by the use of either the dilution or the interchange principle. Meanwhile, Ruzicka, Buijs and Stol13 applied their thorium salt method to the acids fi-CsH4 [(CH2) ...
