Beilstein J. Org. Chem.2017,13, 1050–1063, doi:10.3762/bjoc.13.104
basic. DMF increases solubility of imines 5, while the application of strong acid (HClO4) promotes Shiffbases protonation.
Phenylpyruvic acid (1') was also applied as carbonyl component in GBB-3CR to obtain imidazopyrazoles having a carboxylic group. However, the process of decarboxylation took place
Beilstein J. Org. Chem.2014,10, 722–731, doi:10.3762/bjoc.10.66
; hydrophosphinylation; organo-fluorine; Shiffbases; (trifluoromethyl)phosphinic acid; Introduction
For a long time aminophosphonic and aminophosphinic acids as isosters of aminocarboxylic acids have attracted a particular interest for the preparation of analogues of numerous natural products. Among the literature
reactions with Shiffbases to give adducts 17 in satisfactory yields and these were successfully transformed into the appropriate free acids 14.
The same series of Shiffbases was used to explore the reactivity of ethyl (difluoromethyl)phosphinate (5) in reactions with C=N double bonds and the desired (α
removed during the reaction due to the high acidity of the CF3 phosphinic acid group.
The variability of Schiff bases ensures access to a range of structurally diverse phosphinic acid analogues of amino acids in the relatively simple way. Thus, we investigated the hydrophosphinylation of some Shiffbases
PDF
Graphical Abstract
Scheme 1:
Synthesis of (trifluoromethyl)phosphinic acid (1) and ethyl and isopropyl esters 2–4. Reagents and ...