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Asymmetric michael additions via SAMP/RAMP hydrazones enantioselective synthesis of 2‐substituted 4‐oxophosphonates
Author(s) -
Enders Dieter,
Wahl Heiner,
Papadopoulos Kyriakos
Publication year - 1995
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.1995199507160
Subject(s) - enantioselective synthesis , chemistry , michael reaction , combinatorial chemistry , organic chemistry , catalysis
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.