| Popis: |
We synthetize for the first time the seleno-1 coumarin, a new heterocyclic compound [1]. The chemistry of the thiocoumarins is not very satisfactory. It is possible now to accede easily to thio-1 coumarins as well as seleno-1 coumarins by a general method giving good yields: the cyclization of o-methylthio and o-methylseleno-cinnamic acids. About fifty examples are given. The coumarins are also available from o-methoxycinnamic acids in similar conditions. We show how we arrive to this way and we discuss the mechanism of the cyclization. |
