176504-79-3Relevant academic research and scientific papers
Studies on dioxirane chemoselectivity: The oxidation of an enamino moiety present in a Fischer carbene complex
Lluch, Anna-Maria,Gibert, Mariona,Sanchez-Baeza, Francisco,Messeguer, Angel
, p. 3973 - 3982 (1996)
The dimethyldioxirane (DMD) promoted oxidative decomplexation of Fischer carbene complex 1, which contains a conjugated enamino moiety, was investigted. Thus, treatment of 1 with 3 molecular equivalents of DMD afforded a 52% yield of amide 3 as unique isolable organic product. When the reaction was performed with 1 molecular equivalent of DMD the formation of the enol intermediate 15 was evidenced by its capture as the tetrafluoroboric acid salt 16. This salt was unstable and when it was exposed to air gave rise to amide 3 and to low amounts of ethyl benzoate and acetophenone. These results indicate that the presence of an enamino group conjugated to the Fischer carbene moiety inverts the chemoselectivity previously observed in the DMD promoted decomplexation of these compounds. Thus, the major pathway involves the oxidation of the enamino double bond through the formation of an enol intermediate which reacts with oxygen to give products resulting from the breakdown of the molecule.
Consecutive Three-Component Coupling-Addition Synthesis of β-Amino Enoates and 3-Hydroxypyrazoles via Ethyl 3-Arylpropiolates
Niedballa, Jonas,Reiss, Guido J.,Müller, Thomas J. J.
supporting information, p. 5019 - 5024 (2020/07/24)
Two consecutive three-component syntheses furnishing β-amino enoates or 3-hydroxypyrazoles based upon the Sonogashira alkynylation of aryl iodides and ethyl propiolate were established in mostly excellent yields. The ethyl 3-arylpropiolate intermediates are Michael systems which are suited for concatenation with conjugate addition or cyclocondensation giving access to libraries of 21 different β-amino enoates and 17 different 3-hydroxypyrazoles. The rotational barrier of β-pyrrolidino enoates was assessed by studying the coalescence of pyrrolidinyl protons in VT-NMR spectra of electronically different substituted derivatives showing that the electronic substituent effect on the aryl group does not affect the height of the rotational barrier. This indicates that the substituents are essentially oriented orthogonally to the plane of the β-pyrrolidino enoates.
