Dear Syeda,

Sometimes certain groups such as NH or OH in the vicinity of reaction centre retard or prohibit the reaction. I suggest you to try it by protecting the NH of tetrahydropyridine with easily removable protecting groups like Boc.

All the best.

Hydrazine hydrate deprotonates title acid and its reactivity is weak.

Transfer tetrahydropyridine-2,3-dicarboxylate into cyclic anhydrid, e. g. by reaction with oxalyl chloride in pyridine and try reaction of the cyclic anhydride with hydrazine hydrate, or

try to catalyze the reaction of title acid with hydrazine hydrate by Ce(III) compounds - see 

https://www.researchgate.net/publication/276059289_Kabachnik-Fields_and_Prins-Ritter_Synthesis_Application_of_CeIII_Supported_on_a_Weakly_Acidic_Cation-exchanger_Resin_in_Comparative_Study?ev=prf_pub

https://www.researchgate.net/publication/267390365_Comparative_Studies_of_Catalytic_Application_of_CeriumIII_Chloride_and_Resin_Supported_CeriumIII_in_Domino_Syntheses_of_15-Benzodiazepine_and_13-Diazine_Skeletons?ev=prf_pub

https://www.researchgate.net/publication/265959505_Synergism_of_Metal_and_Organocatalysis_in_Condensation_Reactions_of_Aromatic_Aldehydes_with_Anilines_Affording_Imines_Effect_of_Catalysts_on_the_Base_of_a_Supported_CeriumIII_and_Proline?ev=prf_pub

Article Kabachnik-Fields and Prins-Ritter Synthesis: Application of ...

Article Comparative Studies of Catalytic Application of Cerium(III) ...

Article Synergism of Metal and Organocatalysis in Condensation React...

 Thanks dear Mohammed Ali Hussaini Syed  and Pavel Pazdera, there is no free NH in molecule its N-propyl group, no free acidic group as its dimethyl ester. I saw  a lot of literature having simple reaction of hydrazine with esters where OMe- or OEt- groups of ester being replaced with NH of hydrazine but in my case don't know why is not happening.

Dear Aaliya,

I agree with you that there is an ample amount of literature for the reaction wherein OMe or OEt groups have been knocked off by hydrazine. In fact, it is one of the best ways for the preparation of hydrazides. However, in your case there are two adjacent carboxylate groups and you may have di hydrazide or cyclized species as probable products. I am not sure what transformation you are trying to carry out.

Dear Mohammad you right it is dimethyl 5,5-dimethyl-4-(phenylethynyl)-1-propyl-1,4,5,6-tetrahydropyridine-2,3-dicarboxylate which should react with hydrazine to give 3,3-dimethyl-4-(phenylethynyl)-1-propyl-1,2,3,4,6,7-hexahydropyrido[2,3-d]pyridazine-5,8-dione. You can see structures by putting name into chemdraw.

It can easily replace by reaction of dicarboxylate with 2 to 3 equ, hydrazine hydrate by using methanol as a solvent in reflux condition...

Dear Ashish, I tried that specific condition but no product, that's strange because in literature same kind of reactions are present, don't know why not in my case. :(

Dear Aaliya,

Tetrahydropyridine in general is much less reactive than pyridine. You may try using the anhydride with hydrazine or u may using catalytic amount of HCl(50%).

Good luck

Dear Aaliya

I found an article useful for your case. They using few drops of DMSO in reaction of 1,4-dihydropyridine-3,5-dicarboxylate dervative with thiosemacrbazide in ethanol and refuxing for 10h.

The paper published in European Journal of Medicinal Chemistry 46 (2011) 804e810, by R. Surendra Kumar a, A. Idhayadhulla a, A. Jamal Abdul Nasser a,*, J. Selvin.

Please, find in attach the paper.

Good luck

Dear Talaat, Thank you very much for your valuable suggestion, I tried Acetic acid ac catalyst but didn't work now idea of DMSO addition really attracted me. I'll try this.

Regards

Aaliya

Dear Aliya don't use protic solvents,  you can try in aprotic solvents such as ACN, 1,4-dioxane, DMSO, DMF.

isopropanol is the best solvent.

Dear Syeda

I've an idea to you. First of all try to subject the tetrahydropyridine-2,3-dicarboxylate to be hydrolysed using 10-15% (aq. NaOH) in ethanol and refluxig for 5-6 h. to get the dicarboxylic acid. Second you convert this dicarboxylic acid to diacid chloride by reactiong it with POCl3 and/or SOCl2. Third reacting this diacid chloride with hydrazine hydrate you will get the dicarbohydrazide.

Good luck

tetrahydropyridine-2,3-dicarboxylate with hydrazine hydrate  should give the reaction product by heating on water bath under refluxng conditionisn't successful in refluxing EtOH or MeOH for 2-3 hrs. at 70 deg., cooling it should give the product. Check quality of hydrazine hydrate & diester., repeat the reaction.

Dear Syeda

Did u try using non polar aprotic solvent such as toluene as a sovlent with ?