Evidence and isolation of tetrahedral intermediates formed upon the addition of lithium carbenoids to Weinreb amides and N-acylpyrroles was written by Castoldi, Laura;Holzer, Wolfgang;Langer, Thierry;Pace, Vittorio. And the article was included in Chemical Communications (Cambridge, United Kingdom) in 2017.Reference of 226260-01-1 This article mentions the following:
The tetrahedral intermediates generated upon the addition of halolithium carbenoids (LiCH2X and LiCHXY) to Weinreb amides have been intercepted and fully characterized as O-TMS heminals. The com. available N-trimethylsilyl imidazole is the ideal trapping agent whose employment, combined with a straightforward neutral Alox chromatog. purification, enables the isolation of such labile species. The procedure could be advantageously extended also for obtaining O-TMS heminals from N-acylpyrroles. These intermediates manifest interesting reactivity including as precursors of more complex carbenoids. In the experiment, the researchers used many compounds, for example, 3-Fluoro-N-methoxy-N-methylbenzamide (cas: 226260-01-1Reference of 226260-01-1).
3-Fluoro-N-methoxy-N-methylbenzamide (cas: 226260-01-1) belongs to amides. Compared to amines, amides are very weak bases and do not have clearly defined acid–base properties in water. On the other hand, amides are much stronger bases than esters, aldehydes, and ketones. The presence of the amide group –C(=O)N– is generally easily established, at least in small molecules. It can be distinguished from nitro and cyano groups in IR spectra. Amides exhibit a moderately intense νCO band near 1650 cm−1. By 1H NMR spectroscopy, CONHR signals occur at low fields. In X-ray crystallography, the C(=O)N center together with the three immediately adjacent atoms characteristically define a plane.Reference of 226260-01-1
Referemce:
Amide – Wikipedia,
Amide – an overview | ScienceDirect Topics