The Addition of Grignard Reagents to Pyridazines. VI. The Reaction of tert-Butylmagnesium Chloride with 3,6-Disubstituted-1-methylpyridazinium Iodides.

Titanium-Catalyzed Hydrohydrazination with Monosubstituted Hydrazines: Catalyst Design, Synthesis, and Reactivity

“…The formation of the observed products can be explained as shown in Scheme . We speculate that cyclizations may occur through an allene intermediate under the reaction conditions, which can then undergo either 6- endo or 5- exo trig cyclization, giving rise to 24 or 25 , respectively . An alternative 1,2-insertion pathway involving the alkyne and a titanium hydrazido(1−) of the initial hydrohydrazination product cannot be ruled out under these reaction conditions …”

One-Pot Assembly and Synthetic Applications of Geminal Acyl/Alkoxy Tetrasubstituted Allenes

“…Hydrazine, after condensation to the hydrazone, proceeded to form the pyrazole 1,5-cyclization product 20 , isolated as a mixture of 20 sans benzyloxy fragment and with the benzyloxy intact at the 4-position (85:15 ratio). On the other hand, the analogous N -tosyl hydrazone underwent 1,6-cyclization to form the corresponding 1,5-dihydropyridazine 21 with the benzyloxy group intact; this type of 5-substituted heterocycle is uncommon in the literature. − Finally, Johnson–Corey–Chaykovsky conditions were used to achieve the epoxidation product 22 . , …”