Asymmetric routes toward polyhydroxylated pyrrolidines: Synthesis of 1,4-dideoxy-1,4-imino-d-galactitol and 1,4-dideoxy-1,4-imino-d-glucitol

Stereocontrolled synthesis of new iminosugar lipophilic derivatives and evaluation of biological activities

Iminosugars' similarity to carbohydrates determines the exceptional potential for this class of polyhydroxylated alkaloids to serve as potential drug candidates for a wide variety of diseases such as diabetes, lysosomal storage diseases, cancer, bacterial and viral infections. The presence of lipophilic substituents has a significant impact on their biological activities. This work reports the synthesis of three new pyrrolidine lipophilic derivatives O-alkylated in C-6 position. The biological activities of our iminosugars' collection were tested in two cancer cell lines and, due to the pharmaceutical potential, in the model yeast system Saccharomyces cerevisiae to assess their toxicity.

Total stereocontrolled synthesis of a novel pyrrolizidine iminosugar

Herein we describe a versatile approach to the pyrrolizidine alkaloids skeleton by tailoring our original strategy already used for the pyrrolidine iminosugars synthesis. The key steps are the regio- and stereoselective azidolysis of the suitable chiral vinyl epoxide and then asymmetric dihydroxylation of the corresponding azido alcohol by using (DHQ)₂AQN as the ligand. Further optimized elaborations addressed to the closure of the two rings allowed us to achieve the target iminosugar with complete stereocontrol. The wide range of pyrrolizidine iminosugars' biological properties make them a key focus of new drug research and therefore the development of synthetic strategies for obtaining them is of decisive importance.

Diastereoselective Ritter-like Reaction on Cyclic Trifluoromethylated N,O-Acetals Derived from l-Tartaric Acid

Despite the presence of the highly electron-withdrawing fluorinated substituent, cyclic α-trifluoromethylated N-acyliminium ions were successfully generated from fluorinated O-acetyl-N,O-acetal l-tartaric acid derivatives. The addition of nitriles on these intermediates occurred with high to excellent syn diastereoselectivity and led, in most cases, to oxazolines and amides as single diastereomers. The diastereoselectivity of the addition and the nature of the reaction product depend on the substituents on the hydroxyl groups of the tartaric acid scaffold. This methodology gave access to enantiopure, highly functionalized 5-(trifluoromethyl)pyrrolidin-2-one derivatives, bearing the fluorinated substituent on a tetrasubstituted carbon.