Asymmetric michael additions via SAMP/RAMP hydrazones enantioselective synthesis of 2-substituted 4-oxophosphonates

✍ Scribed by Enders, Dieter ;Wahl, Heiner ;Papadopoulos, Kyriakos

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 979 KB
• Volume: 1995
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.1995199507160

✦ Synopsis

Abstract

Asymmetric Michael addition of lithiated methyl ketone SAMP hydrazones (S)‐3 to a variety of alkenylphosphonates (E)‐2 followed by oxidative cleavage of the 1,4‐adducts (S,S)‐4 by ozonolysis afforded 2‐substituted 4‐oxophosphonates (S)‐5 in usually moderate to very good overall yields (14–77%) and with mostly high enantiomeric excesses (ee = 20–>95%). In addition, asymmetric Michael Michael tandem additions were carried out in good overall yields by trapping the intermediate lithio phosphonate anions with alkenylphosphonate or enoate Michael acceptors.