1994
DOI: 10.1002/jhet.5570310513
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Abstract: Reaction of 3‐methoxy‐ or 3‐chloropyrazine 1‐oxides with refluxing phosphoryl chloride in the presence of amine led to a high regioselective formation of 3‐substituted 2‐chloropyrazines. In contrast, the use of chloroacetyl chloride instead of phosphoryl chloride enabled different regioselectivity to yield 6‐substituted 2‐chloropyrazines, particularly 3‐methoxycarbonylpyrazine 1‐oxide was almost exclusively converted into methyl 6‐chloropyrazinecarboxylate under the conditions without the amine.

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Cited by 16 publications
(11 citation statements)
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“…[14,15] Chloropyrazines can be alkylated with Grignard reagents by Fe(acac) 3 catalysis in a procedure developed by Fürstner et al [13,16] The 2-chloro-6-alkylpyrazines 21a,b were prepared by this method using 1.2 equivalents of methylmagnesium bromide or 2-methylpropylmagnesium bromide, respectively. Reaction with NaOMe in MeOH at 120°C provided the methoxypyrazines 22a,b.…”
Section: Resultsmentioning
confidence: 99%
See 1 more Smart Citation
“…[14,15] Chloropyrazines can be alkylated with Grignard reagents by Fe(acac) 3 catalysis in a procedure developed by Fürstner et al [13,16] The 2-chloro-6-alkylpyrazines 21a,b were prepared by this method using 1.2 equivalents of methylmagnesium bromide or 2-methylpropylmagnesium bromide, respectively. Reaction with NaOMe in MeOH at 120°C provided the methoxypyrazines 22a,b.…”
Section: Resultsmentioning
confidence: 99%
“…Similar to the method of Sato and Fujii, [15] the pyrazine N-oxide was added in small portions to freshly distilled, ice-cooled POCl 3 until the concentration reached 2 mol L -1 . The mixture was heated under reflux for 6 h and then poured onto ice.…”
Section: Preparation Of Chloropyrazinesmentioning
confidence: 99%
“…However, these differences in chemical shifts are less pronounced in compounds 5, 6, 12 and 13 with a chloro atom linked to pyrazine C-3. Here, a safe identification of H-5 and thus the starting point for unambiguous assignments of all carbon atoms can be accomplished by 2D (δ,J) long-range www.interscience.wiley.com/journal/mrc [21] 3, [22,23,24] 4, [23,25] 5, [26,27] 6, [28] 7, [29] 9, [30] 10, [31] 11, [32] 12, [33] 14, [27] INEPT experiments with selective excitation considering the above mentioned characteristic 5 J(CO,H5) coupling. From Table 2 it is apparent that, for 5-9 and 11-13 the absolute value of 2 J(C5,H6) is slightly larger than 2 J(C6,H5); however, the relationship 3 J(C3,H5) > 3 J(C2,H6) is not true stringent in every case.…”
Section: Nmrmentioning
confidence: 99%
“…Most important to note is that mono-oxidation lowers the p K a of the pyrazine ring . Besides this, pyrazine N-oxides can undergo several types of electrochemical and photo–chemical reactions. , They also easily form complexes with metal ions; additionally, oxidation opens new reaction pathways on the pyrazine ring. …”
Section: Resultsmentioning
confidence: 99%