The photoinitiated thiol-ene coupling reactions of 2-substituted glycals had previously been discovered to be a relevant method for stereoselective 1,2-cis-a-thioconjugation preparation. Although all glycals reacted with complete a-selectivity, the reactions’ efficiency varied widely. In our study, we tested the response of thiol-ene addition reaction using thioacetic acid under a variety of conditions. different glycals with different configurations and substituents had been used. Different irradiation methods were also investigated.
The study revealed that the enantiomers react identically with thioacetic acid since there are no chiral components in our reaction. By using diastereoisomers, we could conclude that the reaction of galacto-configured sugar with thioacetic acid is more beneficial than that of the gluco-configured one. The electron-withdrawing substituents decrease the electron density of the double bond which affects the yield negatively. We also found out that the initiator is being consumed, so irradiating the mixture many times while freshly adding the initiator again is the most efficient way to ensure the continuity of the chain reaction. By exploiting these findings, a series of thioglycoside derivatives can be prepared with high yield and complete stereoselectivity, leading to utilize these carbohydrate memetics more in the pharmaceutical industry.