Unexpected Configuration in Stereoselectively Synthesis of Some Novel (1Z)-1-(morpholin-1-yl)-N2-Arylamidrazones

The nucleophilic substitution reaction of hydrazono-N-(aryl)-propanehydrazonyl chlorides 7 with piperidine or morpholine, under the same reaction conditions, resulted in the formation of 1-(piperdin-1-yl / morpholine-1-yl)-N2- arylamidrazones 8a-k, respectively. The X-ray diffraction of piperidin-1-yl-N2-arylamidrazone (8b) confirmed its 1Econfiguration in agreement with the previously reported, whereas X-ray showed the unexpected 1Z-configuration of their analogs, morpholin-1-yl-N2-arylamidrazone (8j). This study established the role of hydrogen bond interaction in the stereochemistry of this class of amidrazones.