Phenanthroline Catalysis in Stereoselective 1,2-cis Glycosylations

Abstract

The scope of phenanthroline catalysis has expanded to f uranosylation, where the diastereoselectivity depends on the faster-reacting phenanthrolinium ion, which eventually forms 1,2-cis f uranoside as the major diastereomer.

Urea‐catalyzed N‐Glycosylation of Amides/Azacycles with Glycosyl Halides

“…A plausible mechanism for 1,2‐ trans ‐selective N ‐glycosylation might result from the S N 2‐type glycosylation via transition state I (Scheme 2), while the 1,2‐ cis ‐selective N ‐glycosylation would involve the formation of a glycosyl pyridinium salt intermediate II [71,72] and a subsequent S N 2‐type N ‐substitution. Recent work by Nguyen et al [66] . indicates an interaction involving pyridinium during glycosyl halide activation, aligning with our hypothesis.…”

“…S N 2-type glycosylation via transition state I (Scheme 2), while the 1,2-cis-selective N-glycosylation would involve the formation of a glycosyl pyridinium salt intermediate II [71,72] and a subsequent S N 2-type N-substitution. Recent work by Nguyen et al [66] indicates an interaction involving pyridinium during glycosyl halide activation, aligning with our hypothesis. Also, this pyridinium appears less prone to interact with potential nucleophiles than TTMPP, potentially preserving their availability for glycosylation.…”

“…Historically, activating these halides demanded stoichiometric amounts of toxic heavy metal salts. However, recent advancements have paved the way for methods that utilize either metal catalysts or organocatalysts, [63][64][65][66][67][68][69] streamlining the Koenigs-Knorr glycosylation reactions. We have demonstrated that urea 1 is a very efficient catalyst for Koenigs-Knorr O-glycosylation (Figure 1a).…”

Stereoselective Synthesis of O-Glycosides with Borate Acceptors

“…Carbohydrates exist widely in nature and play an important role in all kinds of life activities . Numerous pharmaceutical agents involve O -glycoside scaffolds, which are the indispensable components for bioactivity, for example, remogliflozin, lactitol, and heparin . 2-Deoxy O -glycoside derivatives were also found in many biologically relevant natural products and drugs, such as digoxin, amrubicin, and jadomycin .…”

Palladium catalysis enables cross-coupling–like S N 2-glycosylation of phenols

“…Issues can also arise when labile donors or harsh activating conditions are needed, complicating reaction setup. Among the venues to overcome these obstacles, developments include the Yu group (11), which exploits selective gold-alkyne interactions; the Jacobsen group (12,13), which explores mild hydrogen-bond catalysis; the Miller group (14,15), which harnesses the strong Ca-F bond-forming energy; the Nguyen group (16) that employs Lewis base catalysis; and the Codée (17), Takemoto (18), and Loh groups (19), which utilize halogen-bond catalysis, and others based on transition metal catalysis (20,21). We have reported radical activation of glycosyl donors (22).…”