One-Pot Stereoselective Synthesis of C-Glycosyl Amino Acids with Vicinal Stereocenters

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: April 10, 2025

A palladium-catalyzed cascade coupling between glycals and racemic α-nitroesters enables the stereoselective construction of C-glycosyl amino acids bearing two contiguous stereocenters, achieving dual stereocontrol (exclusive β-C1, up to 10:1 diastereomeric ratio at C7). This one-pot protocol room temperature accommodates diverse substrates (25 examples). Mechanistic studies demonstrate that decarboxylation-induced C4-oxyanion directs 1,4-syn selectivity, while steric modulation governs C7 stereochemistry. Synthetic versatility is evidenced by gram-scale synthesis late-stage functionalization trihydroxy C-glycosides, 2,3-dideoxy sugars, 4-O-amino acid conjugates.

Language: Английский

---

Nucleophile-Controlled Regiodivergent Domino Reactions of Enetriones with γ-Bromocrotonates: Access to 1,3-Dienic Esters and Tetrasubstituted Pyrans

The Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: April 23, 2025

Herein, we developed an efficient nucleophile-controlled regiodivergent domino reaction between enetriones and γ-bromocrotonates. This method allowed for the rapid synthesis of a range 1,3-dienic esters tetrasubstituted pyrans under metal-free conditions. In presence pyridine, SN2 substitution/Michael addition/elimination sequence formed in satisfactory yields with high E-stereoselectivities. Alternatively, addition/cyclization/cyclopropanation/cyclopropane ring-opening process forged good help Et3N. It is interesting to note that site-selective reactions γ-bromocrotonates at α- or γ-position were readily realized by modulating pyridine Furthermore, simple Et3N act as both nucleophiles substitution Lewis bases deprotonation processes.

Language: Английский

---

Cobalt-Catalyzed versus Base-Promoted Skeletal- and Stereodivergent Synthesis of Bicyclic α-C-, β-O-, and α-O-Glycosides

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: May 9, 2025

A stereodivergent synthesis of bicyclic α-C-, β-O-, and α-O-glycosides is achieved with nonprecious Co(dpm)3, K2CO3, DBU, respectively. Cobalt-catalyzed decarboxylative allylation 2,3-unsaturated 4-keto glycosyl carbonates 1,3-diketones delivers α-C-glycosides in good yields exclusive chemo- regiocontrol excellent diastereoselectivity (>20:1 dr). K2CO3 enables β-O-glycosides via a cascaded intermolecular Michael addition/SN2-like cyclization, whereas DBU promotes further C5 epimerization to give α-O-glycosides. Mechanistic studies (deuterium labeling intermediate capturing) validate the pathways. Gram-scale late-stage functionalization pharmaceuticals demonstrate practicality.

Language: Английский

---

Tertiary Amine‐Catalyzed Stereoretentive Multi‐Component Cascade Reaction of Carboxylic Acids: Facile Synthesis of Cyclic Ureas/Urethanes

Chinese Journal of Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: May 29, 2025

Comprehensive Summary Herein, we developed a tertiary amine‐catalyzed stereoretentive multi‐component cascade reaction featuring an amidation/[4 + 1] annulation/decarboxylation/Curtius rearrangement/[2 n ] annulation sequence. This metal‐free and step‐economic method provided broad range of cyclic ureas/urethanes in green solvent under mild conditions without employing explosive toxic reagents. Importantly, this generated isocyanates situ catalytic via decarboxylation/Curtius rearrangement process dioxazolones.

Language: Английский

---