Synthetic Approaches to Phosphasugars (2-oxo-1,2-oxaphosphacyclanes) Using the Anomeric Alkoxyl Radical β-Fragmentation Reaction as the Key Step

Abstract

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.

4,5-Dioxo-imidazolinium Cation-Promoted α-Selective Dehydrative Glycosylation of 2-Deoxy- and 2,6-Dideoxy Sugars

“…Commercially available grades of organic solvents are used for column chromatography for purifications. The known compounds 1a , , 1b , , 1c , , 1d , , 1e , , 1f , ,, 1g , , 1h , , 1i , , and 1j showed characterization data in full agreement with previously reported data.…”

Synthesis of 1,2-oxaphosphinane 2-oxides and 1,2-oxaphosphinine 2-oxides: δ-phosphonolactones and δ-phosphinolactones

“…25 The strategy was further utilized in the synthesis of various biologically active phosphasugars and aminophosphasugars in spite of a low stereoselectivity. [26][27][28][29] Scheme 8 Synthesis of optically active 4,5-dimethoxy-2-phenyl-1,2oxaphosphinane 2-oxides from ethyl (2R,3S)-4-benzoyloxy-2,3-dimethoxybutyl(phenyl)phosphinate via the deprotection and intramolecular esterification.…”

“…The strategy was further utilized in the synthesis of various biologically active phosphasugars and aminophosphasugars in spite of a low stereoselectivity. 26–29…”

Syntheses of 1,2‐Oxaphospholane 2‐Oxides and 1,2‐Oxaphosphole 2‐Oxides

“…The optically pure 3-formyloxyderived phosphonates 134 and (phenyl)phosphinates 138 and 140 were first hydrolyzed into the corresponding 3-hydroxy intermediates, which further underwent an acid-catalyzed transesterification to give rise to the corresponding optically active 1,2-oxaphospholane 2-oxides 136 and 137, 139 and 141, respectively (Scheme 34). [59] Condensation of diethyl 2-((diethoxyphosphoryl)methyl)malonate (142) and paraformaldehyde in the presence of the catalytic amount of sodium ethoxide in ethanol generated diethyl 2-((diethoxyphosphoryl)methyl)-2-hydroxymethylmalonate (143), which directly cyclized into diethyl 2-ethoxy-1,2-oxaphospholane-4,4-dicarboxylate 2-oxide (144) in 85 % yield under heating (Scheme 35). [60] Treatment of tetraethyl (1-methoxy-2-(oxiran-2-yl)ethane-1,1-diyl)bis(phosphonate) (145) with bromine and triphenylphosphine in DCM at room temperature gave rise to tetraethyl 4-bromo-3-hydroxy-1-methoxybutane-1,1diyl)bis(phosphonate) (146) and diethyl (5-(bromomethyl)-2ethoxy-3-methoxy-2-oxido-1,2-oxaphospholan-3yl)phosphonate (147) in a ratio of 10 : 90 via nucleophilic ringopening and intramolecular transesterification (Scheme 36).…”