Synthesis and Thermolysis of Cycloalkenyl Azides and Iminophosphoranes Aldehydes: A New Pathway to Bisannelated Pyridines

Nucleophilic substitution on vinyl halides usually occurs when these compounds possess an electron withdrawing group at the D position as well as a good leaving group at the Q position Thus D-chlorovinyl ketones are suitable starting materials for the synthesis of D-azidovinyl ketones' Nesmeyanov and Rybuiskaya2 found that this substitution proceeds with the retention of configuration regarding the C=C bond Consequently, trans-β-halovinyl ketones yield the corresponding trans-D-azido ketones, but very few cis-D-azidovinyl ketone or aldehyde are described3 These latter Isomers have been reported to be unstable and to decompose spontaneously to isoxazoles2 In the case of the cycloalkenyl series β-azidovinyl ketones were only suggested as reaction Intermediatesl,3