2001
DOI: 10.1002/jhet.5570380127
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Free radical 4‐nitrophenylation of thieno[2,3‐b]pyridine. Part 1: General experimental procedure and prediction of isomeric ratios of products

Abstract: Thieno[2,3‐b]pyridine (1) was warmed at 45 ± 7° with diazotized 4‐nitroaniline (2) (molar ratio 1:2 = 3.6:1) in buffered (sodium acetate‐acetic acid) aqueous solution until gas evolution ceased. The reaction mixture was separated into these fractions: (a) water‐soluble (discarded), (b) acetone‐soluble (tars), (c) ether‐soluble, and (d) ether‐ and chloroform‐soluble, but acetone‐insoluble (rust‐colored solids, Y, 12% yield as 4‐nitrophenyl‐1 isomers, 3). Fractional evaporative distillations of (b) and (c) gave … Show more

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Cited by 3 publications
(6 citation statements)
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“…In previous papers in this series [1,2] we described an experimental procedure for the free-radical 4-nitrophenylation of thieno [2,3-b] pyridine (1) by means of the hypothetical intermediate 4-nitrophenyldiazoacetate (2) under buffered conditions to yield a mixture of crystalline monosubstituted 4-nitrophenyl derivatives 3 in 32% yield. Isolated from this mixture were samples of isomerically pure 3a (the 2-isomer) and 3e (the 6-isomer) plus an analy-tically pure sample containing 3a, 3b, and 3c (2-,3-, and 4isomers).…”
Section: Imentioning
confidence: 99%
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“…In previous papers in this series [1,2] we described an experimental procedure for the free-radical 4-nitrophenylation of thieno [2,3-b] pyridine (1) by means of the hypothetical intermediate 4-nitrophenyldiazoacetate (2) under buffered conditions to yield a mixture of crystalline monosubstituted 4-nitrophenyl derivatives 3 in 32% yield. Isolated from this mixture were samples of isomerically pure 3a (the 2-isomer) and 3e (the 6-isomer) plus an analy-tically pure sample containing 3a, 3b, and 3c (2-,3-, and 4isomers).…”
Section: Imentioning
confidence: 99%
“…A Correlaton of Isomeric Selectivities in Electrophilic, Nucleophilic and Free-Radical Substitutions into Thieno[2,3-b]pyridine (1).…”
Section: IVmentioning
confidence: 99%
“…
From the crude mixtures of isomeric 4-nitrophenylthieno [2,3-b]pyridines (3) previously reported [1] were isolated three analytically pure samples, viz. the 2-isomer (yellow needles, mp 258°, 3a), the 6-isomer (red prisms, mp 182°, 3e), and a ternary mixture of the 2-, 3-, and 4-isomers (orange needles, mp 213°, 3a:3b:3c = 1.3:1.0:0.5).
…”
mentioning
confidence: 99%
“…In a preceding paper [1] we reported an experimental procedure for the free-radical 4-nitrophenylation of thieno- [2,3-b]pyridine (1) by means of the hypothetical intermediate 4-nitrophenyldiazoacetate (2) under buffered conditions to yield a mixture of monosubstituted 4-nitrophenyl derivatives 3. Processing of this mixture led to two separable solid, crude products, Y (acetone-insoluble, chloroform-soluble, rust-colored) and Z (acetone-soluble, yellow-red sublimate) in yields of 12% and 20%, respectively.…”
mentioning
confidence: 99%
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