Synthetic approaches to phosphasugars (2-oxo-1,2- oxaphosphacyclanes) using the anomeric alkoxyl radical β‑fragmentation reaction as the key step

Daniel Hernández-Guerra, Alan R. Kennedy, Elisa I. León, Ángeles Martín, Inés Pérez-Martín, María S. Rodríguez, Ernesto Suárez

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The anomeric alkoxyl radical β-fragmentation (ARF) of carbohydrates possessing an electron-withdrawing group (EWG) at C2, promoted by PhI(OAc)2/I2, gives rise to an acyclic iodide through which a pentavalent atom of phosphorus can be introduced via the Arbuzov reaction. After selective hydrolysis and subsequent cyclization, the phosphonate or phosphinate intermediates can be converted into 2- deoxy-1-phosphahexopyranose and 2-deoxy-1-phosphapentopyranose sugars. The ARF of carbohydrates with an electron-donor group (EDG) at C2 proceeds by a radical-polar crossover mechanism, and the cyclization occurs by nucleophilic attack of a conveniently positioned phosphonate or phosphinate group to the transient oxocarbenium ion. This alternative methodology leads to 5-phosphasugars with a 4-deoxy-5-phosphapentopyranose framework. The structure and conformation of the 2-oxo-1,2-oxaphosphinane and 2-oxo-1,2-oxaphospholane ring systems in different carbohydrate models have been studied by NMR and X-ray crystallography.
Original languageEnglish
Pages (from-to)4861-4880
Number of pages20
JournalJournal of Organic Chemistry
Volume85
Issue number7
Early online date16 Mar 2020
DOIs
Publication statusPublished - 3 Apr 2020

Keywords

  • alkoxyl radical β-fragmentation
  • acyclic iodide
  • Arbuzov reaction
  • carbohydrate models

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