N-Thio- and N-selenophenacylamidines: electrophilic activation as a route to some 1-hetero-3-aza-4-dimethylaminobuta-1, 3-dienes

摘要

The preparation of 2-phenyl-4-dimethylamino-1-aza-, 1-oxa-, 1-thia-, 1-selena-3-azabuta-1, 3-dienes as well as their 4-methyl derivatives is described following a new heteroatom interchange reaction process. Heteronucleophilic attack at one particular reactive site of bis-electrophilic amidinium salts is the key feature of the process. In addition, we also disclose that the substituted 1-oxa-3-aza- and 1, 3-diazabuta-1, 3-dienes can be obtained by a reactional transformation cascade initiated by either silver acetate addition or tosyl azide [3 + 2] cycloaddition onto the CS or CSe double bonds of the 1-thia- and 1-selena-3-azabuta-1, 3-diene analogues.