BİFONKSİYONEL ORGANOKATALİZÖRLER VARLIĞINDA TETRAHİDROTİYOFENLERİN ASİMETRİK SENTEZİ

In general, nitroolefins are convenient structures as Michael acceptors. To make it clear for this work, attack of a sulfur-containing nucleophile to a nitroolefin forms a C-S bond and opening the double bond would create a nucleophilic center on the nitroolefin which leads to the formation of a new C-C bond. In this study, asymmetric organocatalytic sulfa-Michael addition of 1,4-dithiane-2,5-diol to trans-β-nitrostyrene derivatives was carried out which yielded polyfunctional tetrahydrothiophenes that have the potential of biological activities, building blocks for chiral ligands and benefit in the synthesis of gold nanoparticles. In the first part, several quinine-based and 2-aminoDMAP-based bifunctional organocatalysts and different conditions were tested to find the optimized conditions for the reaction generating relatively high yield and stereoselectivity in a shorter time. Then, derivatization studies were performed by using diverse trans-β-nitrostyrenes in the optimized conditions determined previously. Increase in stereoselectivity was reached up to 70 % ee and 96:4 dr for the tetrahydrothiophene derivatives.