Background: Enzyme catalysis has always attracted the attention of researchers due to their
unique characteristics and advantages. However, they suffer from disadvantages of being poor in
yield, inoperative and ineffective in aqueous media and suffer from degradation at elevated
temperature. These disadvantages have recently been overcome in new class of catalysts which utilize
same enzyme catalyst power with metal ligand attached to double helical scaffold of DNA. The
process is unique that it can be carried out in aqueous media at room temperature for a range of
organic reactions. In addition to that, process is scalable and has good reproducibility.
Methods: 3+2 Cycloaddition reaction is carried out in water at room temperature using a carefully
selected amount of DNA as catalyst. Reaction is carried out in three schemes. In first scheme, neutral
Platinum Sulfoxide complexes were prepared which are subsequently mixed with 2,2´-bipyrimidine to
form Pt(bipym)Cl2 with 68.8% yield. This is mixed with Cu(II)trifloromethanesulfonate and (E) -
methyl 2 - (benzylideneamino)acetate in a certain sequence to accomplish the reactions. Whole
process takes 6 days with overall yield of 76%.
Results: Completion of reaction as manifested by physical change of color and appearance of peaks in
NMR spectra mark towards effectivity of catalyst. Appearance of peaks occurring at 8, 9.4 and 9.7
ppm showed the presence of CH node resulting from 2 - pyrimidine and 1benzene in one spectrum
while peaks at 7.52, 7.83 and 8.44 ppm show the presence of CH node resulting from benzylidenimin
in second spectra. Further, peaks at 3.68 ppm show the presence of CH3 node resulting from methyl
group and peaks at 4.51 ppm show the presence of CH2 node resulting from methylene group.
Conclusion: This study effectively shows the completion of a difficult to carry 3+2 cycloaddition
reaction in water at room temperature owing to the presence of new class of hybrid catalysts which
combine the power of enzyme catalysts represented by DNA with transition metal ligand attached to
double helix scaffold of DNA to create a synergic effect of enhancement of their effectivity. The study
provided a foot print of their effectivity for new series of reactions.