Nitration of Indoles. III. Polynitration of 2-Alkylindoles<sup>1</sup>

Noland, Wayl­and E.; Smith, Lowell R.; Rush, Kent R.

doi:10.1021/jo01021a044

Cited by 53 publications

(9 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Unfortunately, the synthesis of 1 by the nitration of indole with benzoyl nitrate as reported 5 proceeds in low yield (20-30%) and is plagued by the formation of highly colored side products that complicate purification. More success has been achieved in the synthesis of 3-nitroindoles that are substituted at the C-2 position, including ipso replacement of an azo group, 6 ipso replacement of a 3-acyl group, 7 and direct nitration of 2-phenylindole with 2-cyano-2-propyl nitrate. 8 Since none of these approaches have been extended to C-2 unsubstituted 3-nitroindoles 1 or 2, we decided to examine the nitration of a series of Nprotected indoles 3 with acetyl nitrate.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Reactions of N-Protected 3-Nitroindoles

Pelkey¹,

Gribble²

1999

Synthesis

View full text Add to dashboard Cite

Treatment of N-protected indoles 3 with acetyl nitrate generated in situ at low temperatures affords the corresponding 3-nitroindoles 2 in good to excellent yields. Deprotection of 1-acetyl-3-nitroindole (2h) with DBU gives 3-nitroindole (1). Reaction of 5-chloro-3-nitro-1-(phenylsulfonyl)indole (2k) with ethyl isocyanoacetate and base affords the rearranged ethyl 5-chloro-1,8-dihydro-8-(phenylsulfonyl)pyrrolo[2,3-b]indole-2-carboxylate (5). In contrast, treatment of nitroindoles 2d-f with ethyl isocyanoacetate and base affords the expected pyrrolo[3,4-b]indoles 6-8, the products of a normal Barton-Zard pyrrole synthesis.

show abstract

Section: Methodsmentioning

confidence: 99%

Synthesis and Reactions of N-Protected 3-Nitroindoles

Pelkey¹,

Gribble²

1999

Synthesis

View full text Add to dashboard Cite

show abstract

“…During the synthesis of Indole-3-aldehyde, James and Snyder observed that that the most reactive position on indole for electrophilic aromatic substitution is C-3, which is 10 13 times more reactive than benzene [43]. However, a noteworthy exception took place when Noland, Smith, and Rush, carried out nitration of 2-Phenylindole under acidic conditions [44][45][46][47][48][49][50][51][52]. Electrophilic nitration took place at C-5 (carbocyclic ring), because C-3 of pyrrole ring is protonated.…”

Section: Product Analysis Under Kinetic Conditionsmentioning

confidence: 99%

Trichloroisocyanuric acid and NaNO2 mediated nitration of indoles under acid-free and Vilsmeier–Haack conditions: synthesis and kinetic study

et al. 2019

View full text Add to dashboard Cite

This study deals with the synthetic and kinetic aspects of trichloroisocyanuric acid (TCCA) and NaNO 2 mediated nitration of indoles in aqueous acetonitrile media under acid-free and Vilsmeier-Haack conditions (using N,N′-dimethyl amides) conditions. Nitration of indoles revealed second order kinetics, with a first order dependence on [indole] and [nitrating agent] ([TCCA]/[NaNO 2 ], [(TCCA-DMF)]/[NaNO 2 ] or [(TCCA-DMA)]/[NaNO 2 ], in which [NaNO 2 ] far excess over other reagents). Reactions followed overall second order kinetics with first order in [reagent] and [indole] under the experimental conditions. Isokinetic temperature (β) values were obtained from Leffler's equation for different kinetic protocols (β = 303 K (TCCA-NaNO 2 ); 303 K (TCCA-DMF)/NaNO 2 ; and 244 K (TCCA-DMA)/NaNO 2 ). These values are the experimental temperature range (303-323 K) indicating that the entropy factors are probably more important in controlling the reaction.

show abstract

“…2,3,3-trimethyl-5-nitro-3H-indole (1). 2,3,3-trimethylindole (3.18 g, 0.02 mol) was added into concentrated H 2 SO 4 ( 75 mL) containing HNO 3 (1.70 g, 0.02 mol) within 1 hr and was incubated for 0.5 hr at 0 °C [16]. After reaction, the mixture was poured into ice (1000 mL) to collect the precipatate by suction filtration.…”

Section: Synthesismentioning

confidence: 99%