Enantioselective Deprotonation of Benzyl Phosphates by Homochiral Lithium Amide Bases — Configurational Stability of Benzyl Carbanions with a Dialkoxyphosphoryloxy Substituent and Their Rearrangement to Optically Active α-Hydroxy Phosphonates

✍ Scribed by Hamerschmidt, Friedrich ;Hanninger, Achim

• Publisher: Wiley (John Wiley & Sons)
• Year: 1995
• Tongue: English
• Weight: 829 KB
• Volume: 128
• Category: Article
• ISSN: 0009-2940
• DOI: 10.1002/cber.19951280814

✦ Synopsis

Benzyl dialkyl phosphates are deprotonated enantioselec-up to 50%. The pro-(S) hydrogen is removed by amides hatively by homochiral lithium amides of isopropyl( 1-phenyl-ving (S) configuration. Homochiral diethyl (S)-phenyl[D+ ethy1)amine or bis(1-phenylethy1)amine. The short-lived ben-methyl phosphate [(S)-16c] is deprotonated by both LDA and zylic carbanions formed are virtually configurationally stable n-BuLi with a high primary kinetic isotope effect (kwD = 50) relative to the rearrangement to optically active phenyl-and isomerizes to the corresponding a-hydroxy phosphonate hydroxymethylphosphonates. The enantiomeric excesses are with an enantiomeric excess of up to 85 YO.