Synthesis of Mono‐ and Bis‐Thiourea Organocatalysts and Their Application in Stereoselective Glycosylation Reactions

Abstract Two new mono‐thiourea, four bis‐thiourea and one squaramide organocatalysts were synthesised from L‐tartaric acid. These organocatalysts were able to activate glycosyl phosphates for stereoselective nucleophilic substitution reactions with broad functional group compatibility under mild conditions. The influence of the number and position of the thiourea groups and the proximity of the asymmetric centre to the catalytic important atoms for the stereoselective outcome of the glycosylation reactions was studied. 1,2‐ cis Glycosides were obtained in up to 85 % yield and high diastereoselectivity (up to α:β 83 : 17).