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The reaction conditions for the Kröhnke synthesis are generally facile and the reactions often proceed in high yields with reaction temperatures generally not exceeding 140 °C. [6] The Kröhnke synthesis is generally performed in either glacial acetic acid or methanol, but it can also be done under aqueous conditions, and more recently under ...
This was the first synthesis of a heteroaromatic compound. [24] [40] The first major synthesis of pyridine derivatives was described in 1881 by Arthur Rudolf Hantzsch. [41] The Hantzsch pyridine synthesis typically uses a 2:1:1 mixture of a β-keto acid (often acetoacetate), an aldehyde (often formaldehyde), and ammonia or
It contains a molybdenum(VI) center with multiple oxygen ligands, coordinated with pyridine and HMPA ligands, although the HMPA can be replaced by DMPU. [2] It is an electrophilic source of oxygen that reacts with enolates and related structures, and thus can be used for alpha- hydroxylation of carbonyl -containing compounds. [ 3 ]
Pyridine-N-oxide is the heterocyclic compound with the formula C 5 H 5 NO. This colourless, hygroscopic solid is the product of the oxidation of pyridine. It was originally prepared using peroxyacids as the oxidising agent. The compound is used infrequently as an oxidizing reagent in organic synthesis. [1]
Original reactions reported by Baeyer and Villiger. There were three suggested reaction mechanisms of the Baeyer–Villiger oxidation that seemed to fit with observed reaction outcomes. [16] These three reaction mechanisms can really be split into two pathways of peroxyacid attack – on either the oxygen or the carbon of the carbonyl group. [17]
The mechanism of the Boekelheide reaction begins by an acyl transfer from the trifluoroacetic anhydride to the N-oxide oxygen. The α-methyl carbon is then deprotonated by the trifluoroacetate anion. This sets the molecule up for a [3.3]-sigmatropic rearrangement which furnishes the trifluoroacetylated methylpyridine. Hydrolysis of the ...
Directed metallation is not limited to lithium intermediates or even to an ortho preference. In one study [13] it is found that the reaction product of N,N-dimethylaniline with a complex of TMEDA, sodium salt of TMP and di-tert-butylzinc is a meta zincated complex as a stable crystalline compound.
4-Methylpyridine is the organic compound with the formula CH 3 C 5 H 4 N. It is one of the three isomers of methylpyridine. This pungent liquid is a building block for the synthesis of other heterocyclic compounds. Its conjugate acid, the 4-methylpyridinium ion, has a pK a of 5.98, about 0.7 units above that of pyridine itself. [1]