Synthesis of d-Fagomine and Its Seven- and Eight-Membered Higher-Ring Analogues, and the Formal Synthesis of (+)-Australine from l-Xylose-Derived Chiron

Abstract

‡ These authors contributed equally to this work. H N HO HO OH D-fagomine HN HO HO OH HN HO HO OH N HO HO OH OH (+)-australine BnO OBn OH BnO L-xylose O HO OH OH HO AbstractThe synthesis of D-fagomine and its seven-and eight-membered higher-ring analogues from commercially available L-xylose is reported. The syntheses involve elaboration of a common alkenol precursor obtained from L-xylose-derived hemiacetal. The key steps in the syntheses are intramolecular reductive amination and ring-closing metathesis for the synthesis of D-fagomine and seven-/eight-membered iminosugar, respectively. We have also extended our synthetic strategy for the formal synthesis of (+)-australine using zinc-mediated fragmentation reaction and ring-closing metathesis as key steps.

Intramolecular Palladium-Catalyzed Carboamination for the Stereoselective Synthesis of Five-Membered Iminosugar C-Glycosides

“…[α] D 20 = +11.8 ( c = 1.50, CHCl 3 ). 1 H and 13 C NMR spectra of compound (4 S )- 4 are in accordance with literature data …”

“…1 H and 13 C NMR spectra of compound (4S)-3 are in accordance with literature data. 25 2-((1R,2S,3S)-2,3-Dibenzyloxy-1-(benzyloxymethyl)pent-4-enyl)isoindoline-1,3-dione ((4R)-3). From alcohol (4S)-2 (532 mg, 1.27 mmol) following the general procedure for Mitsunobu reaction, the product (4R)-3 (488 mg, 70%) was isolated as a colorless viscous oil.…”

NbCl5-catalyzed sulfa-Michael addition for constructing quaternary centers in enones

“…In recent decades, many efficient sulfa-Michael additions have been widely reported using thiols as nucleophiles to attack various Michael acceptors. 1–4 By summarizing these works, we found that the published approaches could be divided into four different pathways: transition metal catalysis, 1 organocatalysis, 2 green chemistry methods, 3 and heterogeneous catalysis. 4 However, most methods focused on adding thiols to di-substituted Michael acceptors, constructing tertiary centers.…”