scholarly journals Further enhancement of the clickability of doubly sterically-hindered aryl azides by para-amino substitution

2018 ◽  
Vol 54 (96) ◽  
pp. 13499-13502 ◽  
Author(s):  
Suguru Yoshida ◽  
Junko Tanaka ◽  
Yoshitake Nishiyama ◽  
Yuki Hazama ◽  
Takeshi Matsushita ◽  
...  
Keyword(s):  
Amino Group ◽  
Aryl Azides ◽  
Sterically Hindered

Introduction of an amino group at the para position of doubly sterically-hindered aryl azides significantly enhances their clickability with cyclooctynes.

Hydrogen Bonding in organic compounds. 1. o-Nitroanilines

1958 ◽  
Vol 11 (4) ◽  
pp. 513 ◽  
Author(s):  
LK Dyall ◽  
AN Hambly
Keyword(s):  
Hydrogen Bonding ◽  
Nitro Group ◽  
Organic Compounds ◽  
Intramolecular Hydrogen Bonding ◽  
Amino Group ◽  
Infra Red ◽  
Sterically Hindered ◽  
Intramolecular Hydrogen

The infra-red spectra of o-nitroanilines do not indicate any intramolecular hydrogen bonding unless there are nitro groups in both positions 2 and 6 to the amino group. An examination of the literature shows that there is no unambiguous evidence from other sources of such bonding in simple o-nitroanilines. An explanation is given of the variation of the stretching frequencies of the nitro group in sterically hindered compounds and in those with electron-donating ortho- and para-substituents.

Unusual formation of sterically hindered primary amines in a series of pyrrolo- and pyrido[1,2-a]indoles

1991 ◽  
Vol 56 (11) ◽  
pp. 2278-2287 ◽  
Author(s):  
Ivo Jirkovsky ◽  
Lynne Greenblatt ◽  
Reinhardt Baudy
Keyword(s):  
Pyridine Ring ◽  
Primary Amines ◽  
Amino Group ◽  
Sterically Hindered ◽  
Similar Preparation ◽  
Unusual Formation

2,3-Dihydro-2,2,9-trimethyl-1H-pyrrolo[1,2-a]indol-1-amine and its 1-(1-pyrrolidinyl) analog have been synthesized from the corresponding 1-ol via mesylation in pyridine followed by treatment with pyrrolidine. Mechanisms of the former, unexpected amination are briefly discussed. Evidence is presented that the pyridine ring serves as a masked amino group. The phenomenon is partly attributed to steric congestion. Similar preparation of 2-bromo-6,7,8,9-tetrahydro-8,8,10-trimethylpyridol[1,2-a]indol-9-amine supports this notion.

scholarly journals Enhanced clickability of doubly sterically-hindered aryl azides

2011 ◽  
Vol 1 (1) ◽  
Author(s):  
Suguru Yoshida ◽  
Akira Shiraishi ◽  
Kimiyuki Kanno ◽  
Takeshi Matsushita ◽  
Kohei Johmoto ◽  
...  
Keyword(s):  
Aryl Azides ◽  
Sterically Hindered

Pyrolysis of aryl azides. IV. Neighbouring group effects by ortho carbonyl groups

1977 ◽  
Vol 30 (12) ◽  
pp. 2669 ◽  
Author(s):  
LK Dyall
Keyword(s):  
Carbonyl Groups ◽  
Aryl Azides ◽  
Phenyl Azide ◽  
Sterically Hindered ◽  
Group Effects

The question of the mechanism by which ortho carbonyl groups enhance the rate of pyrolysis of aryl azides is examined. Rate measurements on sterically hindered 1-(2-azidophenyl)ethan-1-ones are consistent with the pericyclic mechanism proposed by Dyall and Kemp1 but not with the intramolecular 1,3-dipolar addition route put forward by Hall, Behr and Reed.2 A definitive test of mechanism is also provided by 1- azidoanthraquinone and 1-(2-azidophenyl)-2,2-dimethylpropan-1-for both of which the formation of a 1,3-dipolar adduct is precluded on steric grounds but the pericyclic process is not. At 393.2 K, these two azides pyrolyse 7385 and 61.7 times faster than phenyl azide, respectively.

Synthesis and properties of some gelatin derivatives with substituents at the amino group

1965 ◽  
Vol 15 (10) ◽  
pp. 479-488
Author(s):  
R. C. Clark ◽  
W. G. Cobbett ◽  
J. A. Gibbs ◽  
R. T. Jones ◽  
A. A. Leach ◽  
...  
Keyword(s):  
Amino Group

Nickel-Catalyzed Regioselective Hydroalkylation of 1,3-Dienes with Hydrazones

2019 ◽  
Author(s):  
Leiyang Lv ◽  
Dianhu Zhu ◽  
Zihang Qiu ◽  
Jianbin Li ◽  
Chao-Jun Li
Keyword(s):  
Catalytic Method ◽  
Unsaturated Hydrocarbons ◽  
Carbon Nucleophiles ◽  
Aryl Aldehydes ◽  
Aldehydes And Ketones ◽  
Sterically Hindered

Hydroalkylation of unsaturated hydrocarbons with unstablized carbon nucleophiles is difficult and remains a major challenge. The disclosed examples so far mainly focused on the involvement of heteroatom and/or stabilized carbon nucleophiles as efficient reaction partners. Reported here is an unprecedented regioselective nickel-catalyzed hydroalkylation of 1,3-dienes with hydrazones, generated in situ from abundant aryl aldehydes and ketones and acted as both the sources of unstabilized carbanions and hydride. With this strategy, both terminal and sterically hindered internal dienes are hydroalkylated efficiently in a highly selective manner, thus providing a novel and reliable catalytic method to construct challenging C(sp3)-C(sp3) bonds.

Synthesis of Conjugated Triynes via Alkyne Metathesis

2019 ◽  
Author(s):  
Idriss Curbet ◽  
Sophie Colombel-Rouen ◽  
Romane Manguin ◽  
Anthony Clermont ◽  
Alexandre Quelhas ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Selectivity ◽  
Alkyne Metathesis ◽  
Cross Metathesis ◽  
Synthetic Strategy ◽  
Sterically Hindered ◽  
Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

Aminocoumarins: A Privileged Precursor for the Synthesis of Fused Heterocycles

2019 ◽  
Vol 23 (9) ◽  
pp. 1045-1075 ◽  
Author(s):  
Saigal ◽  
Sumbulunnisan Shareef ◽  
Habibur Rahman ◽  
Md. Musawwer Khan
Keyword(s):  
Chemical Reactivity ◽  
Structural Systems ◽  
Natural Occurrence ◽  
Amino Group ◽  
Active Compounds ◽  
The Past ◽  
Fused Heterocycles

Aminocoumarins are one of the important core structural systems, present in several biologically and medicinally active compounds. Owing to its natural occurrence, potential pharmacological applications and remarkable versatility as a privileged precursor, several proficient synthetic protocols have been reported in the literature over the past years. The presence of an amino group and enamine carbon enhances its chemical reactivity and thus such functionality is repeatedly used for the construction of various fused and simple heterocycles. This review highlights the preparation of different aminocoumarins and their applications for the construction of a variety of five, six and eight membered fused heterocycles.

Substituent Effects on the Basicity of ortho-, meta- and para-substituted N1,N1-Dimethyl-N2-phenylformamidines in Ethanol and in Water

1992 ◽  
Vol 57 (1) ◽  
pp. 113-118
Author(s):  
Ewa Daniela Raczyńska
Keyword(s):  
Quantitative Analysis ◽  
Aqueous Ethanol ◽  
Substituent Effects ◽  
Amino Group

The relative δpKa values of ortho-, meta-, and para-substituted N1,N1-dimethyl-N2-phenylformamidines obtained in 95.6% aqueous ethanol have been compared with those in water. The comparison shows only some differences in the ortho substituent effects. The meta and para substituent effects in ethanol are not very different from those in water. Quantitative analysis of the experimental δpKa values based on the Taft equation has led to separation of the total electromeric effects into the inductive and mesomeric effects. As compared to the amino group in anilines, the formamidine group is more sensitive to the transmission of the inductive than the mesomeric effects.

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