This study was made in an effort to elucidate further the question of whether a cyclopropane ring can participate in transmission of conjugation between one contiguous unsaturated group and another attached to a different carbon atom of the ring. Analyses of the product mixtures from reactions oftypical nucleophiles with diethyl 2-vinylcyclopropane-1, 1-dicarboxylate have shown that in some cases such transmission does occur, resulting in 1,6 addition to the system being studied. Uncatalyzed reactions of thiols gave exclusively 1,6-addition products, base-catalyzed reactions of thiols gave mixtures of 1,6-addition products and 1,4-addition products resulting from simple ring opening, and reactions of amines gave only 1,4-addition products. © 1969, American Chemical Society. All rights reserved.