A Domino Epoxide Ring‐Opening Xanthate Migration Reaction: An Alternative Entry to Thiosugars

Abstract

A sterereospecific and efficient synthesis of thiosugars derived from levoglucosenone and methyl α‐d‐glucopyranoside was developed by a domino epoxide ring opening‐ xanthate migration to afford 1,3‐oxathiolane‐2‐thiones in high yields. The stereochemical outcome of the new C–S bond was defined by the configuration of the starting materials. The 1,3‐oxathiolane‐2‐thiones were subsequently submitted to a second tandem reaction affording the corresponding 2,3‐episulfide alcohols. The thiosugars obtained are useful building blocks for the synthesis of thiooligosaccharides with potential biological properties.

Tuning zirconia-supported metal catalysts for selective one-step hydrogenation of levoglucosenone

“…Levoglucosenone has been proved to be an excellent chiral scaffold for the preparation of useful organic compounds due to the large number of works demonstrating its application as starting material for the synthesis of bioactive compounds, disaccharides and chiral inductors for asymmetric synthesis. [15][16][17][18] In this work, the spotlight has been put on the hydrogenation opportunities that heterogeneous catalysts based on supported metals could offer for levoglucosenone, with the aims of continuing opening new research lines for the valorisation of this compound and giving new tools for organic chemists in its use as a raw material for complex organic synthesis involving multiple steps.…”

Synthesis and applications of the sulfur containing analogues of cyclic carbonates

“…10d). 60,61 In these reports the cis -epoxy alcohol formed the expected xanthate leaving the epoxide ring unreacted, whilst the trans -epoxy alcohol yielded the desired 1,3-oxathiolane-2-thione product with migration of the xanthate group. The authors proposed a rational mechanism to explain these observations, based on the inherent stereochemistry of the starting material.…”

The Synthesis and Glycoside Formation of Polyfluorinated Carbohydrates

“…Studies by the Tsuchiya group regarding the regioselective opening of 2,3-anhydroallopyranoside derivatives such as 372 led to the synthesis of 2,6-dideoxy-2,6-difluoroaltrose derivatives (Scheme ). The epoxy intermediate 370 , which can be obtained from methyl glucoside 369 in four steps via selective OH-3 tosylation, base-mediated epoxide formation, and hydrolysis, was selectively methylated at the 4-position to give 371 . Its deoxyfluorination led to 372 , which was further fluorinated by reaction with KHF 2 in ethylene glycol to give an inseparable mixture of the altro -derivative 373 and the gluco -derivative 374 in a 2:3 ratio .…”