Stereoselective Synthesis of α‐Monofluorinated Phosphonate Mimetics of Naturally Occurring Phosphoserine and Phosphothreonine, via Electrophilic Fluorination of Lithiated Bis‐lactim Ethers.

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

“…18 The lithium borohydride reduction of ethyl 2-((tert-butoxycarbonyl)amino)-4-(diethoxyphosphoryl)-4-fluorobutanoates gave rise to 5-Boc-amino-2-ethoxy-3-fluoro-1,2-oxaphosphinane 2-oxides in 75-90% yields in THF via reduction of the ester group into the hydroxyl group and subsequent transesterification (Scheme 7). 19 The phosphaesterification strategy was widely applied in the synthesis of different phosphasugars. [20][21][22] The intramolecular esterification of ethyl (2R,3S)-4-benzoyloxy-2,3-dimethoxybutyl(phenyl)phosphinate directly occurred by treatment with sodium ethoxide for the deprotection of the benzoyl group, affording a pair of diastereomeric 4,5dimethoxy-2-phenyl-1,2-oxaphosphinane 2-oxides (Scheme 8).…”