16 16 strong mutagens, with the bay-region (1, 2-) derivative being 4-5 times as mutagenic as the nonbay (3, 4-) epoxide in S. typhimurium strain TA 100. By studying these two series of epoxides, it should be possible to discern whether patterns of activation exist. For example, electronic stabilization of the carbocation formed at C1 by ring opening of the 1, 2- epoxide should be greater than that of the carbocation formed at C4 by ring opening of the ...