Design, Synthesis and Spectroscopic Characterizations of Medicinal Hydrazide Derivatives and Metal Complexes of Malonic Ester

Background: A new series of malonic acid-based hydrazide derivatives (BPMPDH, 2HPMPDH, 3HPMPDH, 4HPMPDH, DMPDH) are successfully synthesized by the reaction of malonic ester hydrazide with various substituted aldehydes like salicylaldehyde, benzaldehyde, 4-hydroxy benzaldehyde, 3-hydroxy benzaldehyde and formaldehyde) Methods: metal complexes of prepared hydrazide derivatives were prepared using metals like Cu+2, Zn+2 and Ni+2 via a mild, efficient and convenient method. Newly synthesized compounds were characterized by IR, NMR (1H & 13C), UV/VIS and mass spectrometry. The presence of –C=N- peak at 1600-1700 cm-1 with the absence of NH2 peak at 3500 cm-1 in FTIR spectra. In 1HNMR peak at, 11.00-13.00 ppm for –OH protons and 7.00-9.50 ppm for –NH verified the synthesis of new hydrazide derivatives. The presence of a C-OH sharp peak at 180-190 ppm, a C=O peak at 160-170 ppm and a C=N peak at 140-150 ppm confirmed synthesis. In mass spectra, the molecular ion peaks at 308 m/z, 340 m/z and 156 m/z confirmed synthesis. Synthesized compounds have also been analyzed for their antioxidant, antibacterial, antifungal, chymotrypsin and tyrosinase inhibition activities Result and Conclusion: The results revealed that the 2HPMPDH, 3HPMPDH, 4HPMPDH and their Cu+2 and Zn+2 metal complexes showed more successful inhibition against standard drugs, based on structure activity relationship.

Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts

This work presents the synthesis of six new phase-transfer organocatalysts in which the squaramide unit is directly linked to the nitrogen atom of an aza-crown ether. Four chiral skeletons, namely hydroquinine, quinine, cinchonine (cinchonas), and α-d-glucopyranoside were responsible for the asymmetric construction of an all-carbon quaternary stereogenic center in α-alkylation and Michael addition reactions of malonic esters. We investigated the effects of these different chiral units and that of crown ethers with different sizes on catalytic activity and enantioselectivity. During extensive parameter investigations, both conventional and emerging green solvents were screened, providing valuable α,α-disubstituted malonic ester derivatives with excellent yields (up to 98%).

Use of Ethyl (Benzothiazol-2-ylsulfonyl)acetate for Malonic Ester-type Syntheses of Carboxylic Acids and Esters

A new methodology for the synthesis of substituted carboxylic acids is described. Alkylation of either ethyl (benzothiazol-2-ylsulfonyl)acetate or ethyl 2-(benzothiazol-2-ylsulfonyl)propionate was achieved with alkyl halides and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dichloromethane solution. These products were then desulfinated and hydrolysed in one-pot under mild conditions to give substituted acetic acids in good-to-excellent yields.

N-Heterocyclic carbene-catalyzed enantioselective synthesis of functionalized cyclopentenes via α,β-unsaturated acyl azoliums

Highly enantioselective NHC-organocatalyzed synthesis of functionalized cyclopentenes by the reaction of modified enals with malonic ester derivatives having a γ-benzoyl group is reported.