Hydrazides reaction with alkenes

Electrophilic substitution of the ring hydrogen atom in 1,3,4-oxadiazoles is uncommon. In contrast, several reactions of electrophiles with C-linked substituents of 1,3,4-oxadiazole have been reported. 2,5-Diaryl-l,3,4-oxadiazoles are bromi-nated and nitrated on aryl substituents. Oxidation of 2,5-ditolyl-l,3,4-oxadiazole afforded the corresponding dialdehydes or dicarboxylic acids. 2-Methyl-5-phenyl-l,3,4-oxadiazole treated with butyllithium and then with isoamyl nitrite yielded the oxime of 5-phenyl-l,3,4-oxadiazol-2-carbaldehyde. 2-Chloromethyl-5-phenyl-l,3,4-oxadiazole under the action of sulfur and methyl iodide followed by amines affords the respective thioamides. 2-Chloromethyl-5-methyl-l,3,4-oxadia-zole and triethyl phosphite gave a product, which underwent a Wittig reation with aromatic aldehydes to form alkenes. Alkyl l,3,4-oxadiazole-2-carboxylates undergo typical reactions with ammonia, amines, and hydrazines to afford amides or hydrazides. It has been shown that 5-amino-l,3,4-oxadiazole-2-carboxylic acids and their esters decarboxylate. 

There is one useful case of the second disconnection. Maleic anhydride 180 has to have a Z alkene because of its cyclic structure. Reaction with hydrazine gives a diamide 181 that prefers to exist as 182 and is known as maleic hydrazide . 

The products from the reaction of alkene diazonium salts (266 X = SbCle or BF4) with acyl hydrazides are dependent on the nature of the substituents (R and R ) on the alkene <85CB4026, 89ZN(B)587>. With the 4-methoxystyryl derivative (266 R =OMe, R = 4-MeOQH4) only 1,3,4-oxadiazoles (267) are produced (17-40%), whereas with ketene acetals (266 R = OMe, R = OEt)... 

MeAlCl2 has been used as the catalyst for epoxide-initiated cation-alkene cyclizations. A tertiary alcohol has been converted to a hydrazide by reaction with MeAlC in the presence of MesitylenesulfonyUiydroTide. a-Trimethylsilyl enones can be prepared by isomerization of l-(trimethylsilyl)-2-propynyl trimethylsilyl ethers with MeAICl2. ... 

In a typical reaction a concentrated solution of polymer in a solvent such as diglyme is heated with an excess of p-toluene sulphonyl hydrazide. The diimide is generated in situ to react with the alkene as indicated in the following scheme ... 

---