An Efficient Method for the Oxidation of Aryl Substituted semicarbazides to aryl azo compounds with NaNO2-Ac2O

2002 ◽  
Vol 2002 (6) ◽  
pp. 284-285 ◽  
Author(s):  
Xiao-Chuan Li ◽  
Yu-Lu Wang ◽  
Jin-Ye Wang
Keyword(s):  
Acetic Anhydride ◽  
Efficient Method ◽  
Azo Compounds ◽  
Oxidizing Agent ◽  
Mild Conditions ◽  
First Time

In this paper 18 aryl substituted semicarbazides undergo rapid oxidation to the corresponding aryl azo compounds using NaNO2-acetic anhydride as a novel oxidizing agent under mild conditions for the first time.

A Simple and Efficient Method for the Dehydrogenation of Symmetric Hydrazo Compounds with NaNO2/NaHSO4•H2O/SiO2

2002 ◽  
Vol 2002 (11) ◽  
pp. 540-541 ◽  
Author(s):  
Xiao-Chuan Li ◽  
Yu-Lu Wang ◽  
Jin-Ye Wang
Keyword(s):  
Efficient Method ◽  
Azo Compounds ◽  
Mild Conditions ◽  
First Time

In this paper, 18 symmetric hydrazo compounds undergo rapid oxidation to corresponding azo compounds using NaNO2/NaHSO4•H2O/SiO2 as a novel oxidising agent under mild conditions for the first time.

Copper-Catalyzed Highly Efficient Esterification of Aldehydes with N-Hydroxyphthalimide via Cross-Dehydrogenative Coupling in Water at Room Temperature

Synlett ◽  
2017 ◽  
Vol 28 (11) ◽  
pp. 1321-1326 ◽  
Author(s):  
Can Jin ◽  
Weike Su ◽  
Zhicheng Guo ◽  
Xinpeng Jiang ◽  
Jiadi Zhou ◽  
...  
Keyword(s):  
Reaction Time ◽  
Efficient Method ◽  
Room Temperature ◽  
Coupling Reaction ◽  
Short Reaction Time ◽  
Mild Conditions ◽  
Highly Efficient ◽  
Dehydrogenative Coupling ◽  
First Time

A copper-catalyzed cross-dehydrogenative coupling reaction between N-hydroxyphthalimide and aldehydes using PhI(OAc)2 as an oxidant is described. It is reported for the first time to synthesize NHPI esters in water, providing the corresponding NHPI esters in moderate to good yields. This facile and efficient method is eco-friendly and possesses the advantages of mild conditions, short reaction time, and broad substrate scope.

An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

1991 ◽  
Vol 56 (12) ◽  
pp. 2917-2935 ◽  
Author(s):  
Eva Klinotová ◽  
Václav Křeček ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Spectral Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Condensation Products ◽  
Unsaturated Lactones ◽  
C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

Copper and triphenylphosphine-promoted sulfenylation of quinones with arylsulfonyl chlorides

RSC Advances ◽  
2016 ◽  
Vol 6 (67) ◽  
pp. 62298-62301 ◽  
Author(s):  
Xiaoli Yu ◽  
Qiujin Wu ◽  
Huida Wan ◽  
Zhaojun Xu ◽  
Xingle Xu ◽  
...  
Keyword(s):  
Mild Conditions ◽  
First Time

The copper and triphenylphosphine-promoted sulfenylation of quinones with arylsulfonyl chlorides has been developed under mild conditions with moderate to good yields. This is the first time to prepare arylthioquinones with arylsulfonyl chlorides.

Photochemical reactions of azo compounds. IX. Further studies related to the photochemical reactions of bisazo compounds

1967 ◽  
Vol 20 (2) ◽  
pp. 321 ◽  
Author(s):  
NC Jamieson ◽  
GE Lewis
Keyword(s):  
Sulphuric Acid ◽  
Photochemical Reaction ◽  
Photochemical Reactions ◽  
Azo Compounds ◽  
Bisazo Compounds ◽  
First Time

The photochemical reactions of 4,4?-bis(phenylazo)biphenyl and 4- phenyl-azoazobenzene in 98% sulphuric acid have been examined, for comparison with the corresponding reactions in 22N acid. Photochemical cyclodehydrogenation of 4-phenylazoazobenzene to two benzo[c]cinnoline derivatives has thereby been effected for the first time. The observed course of the latter reaction has led, in turn, to studies of the benzidine rearrangement of 2-(2-phenylhydrazino)benzo[c]- cinnoline, of the photochemical cyclodehydrogenation of 3-phenylazobenzene, and of the photochemical reaction of 2-phenylazobenzo[c]cinnoline. The results of these investigations are now recorded and discussed.

STATISTICAL CHARACTERISTICS OF SLANT ANGLES IN HANDWRITTEN NUMERAL STRINGS AND EFFECTS OF SLANT CORRECTION ON SEGMENTATION

2010 ◽  
Vol 24 (01) ◽  
pp. 97-116 ◽  
Author(s):  
JAVAD SADRI ◽  
CHING Y. SUEN ◽  
TIEN D. BUI
Keyword(s):  
Efficient Method ◽  
Weighted Average ◽  
Correction Method ◽  
Statistical Characteristics ◽  
Geometric Features ◽  
Correction Algorithm ◽  
Connected Component ◽  
Slant Angle ◽  
Segmentation Accuracy ◽  
First Time

A novel and efficient method for correction of slant angles in handwritten numeral strings is proposed. For the first time, the statistical distribution of slant angles in handwritten numerals is investigated and the effects of slant correction on the segmentation of handwritten numeral strings are shown. In our proposed slant correction method, utilizing geometric features, a Component Slant Angle (CSA) is estimated for each connected component independently. A weighted average is then used to compute the String Slant Angle (SSA), which is applied uniformly to correct the slant of all the components in numeral strings. Our experimental results have revealed novel statistics for slant angles of handwritten numeral strings, and also showed that slant correction can significantly improve extraction of segmentation features and segmentation accuracy of touching numerals. Comparison between our slant correction algorithm and similar algorithms in the literature show that our algorithm is more efficient, and on average it has a faster running time.

Ni-catalyzed direct iminoalkynylation of unactivated olefins with terminal alkynes: facile access to alkyne-labelled pyrrolines

2021 ◽  
Author(s):  
Xingjie Zhang ◽  
Di Qi ◽  
Chenchen Jiao ◽  
Zhiguo Zhang ◽  
Xiaopan Liu ◽  
...  
Keyword(s):  
Radical Cyclization ◽  
Terminal Alkynes ◽  
Mild Conditions ◽  
Type Coupling ◽  
First Time

The direct iminoalkynylation of unactivated olefins with terminal alkynes is achieved for the first time by nickel-catalyzed cascade iminyl-radical cyclization/Sonogashira-type coupling of γ,δ-unsaturated oxime esters under mild conditions. This transformation...

Organophosphane-Catalyzed Construction of Functionalized 2-Ylideneoxindoles via Direct β-Acylation

Synthesis ◽  
2021 ◽  
Author(s):  
Wey-Chyng Jeng ◽  
Po-Chung Chien ◽  
Sandip Sambhaji Vagh ◽  
Athukuri Edukondalu ◽  
Wenwei Lin
Keyword(s):  
Intramolecular Cyclization ◽  
Efficient Method ◽  
Bond Cleavage ◽  
Scale Up ◽  
Acyl Chlorides ◽  
Metal Free ◽  
Mild Conditions ◽  
Synthetic Utility ◽  
Mechanistic Investigations ◽  
Synthetic Transformations

We report an efficient method for the direct β-acylation of 2-ylideneoxindoles with acyl chlorides in the presence of base-catalyzed by organophosphanes. A variety of functionalized 2-ylideneoxindoles were prepared in moderate to good yields under metal-free and mild conditions via a tandem phospha-Michael/O-acylation/intramolecular cyclization/ rearrangement sequence. The mechanistic investigations revealed that the C-O bond cleavage on possible betaine intermediate is the key step for the installation of keto-functionality at β-position of 2-ylideneoxindoles in a highly stereospecific manner. The synthetic utility of this protocol could also be proven by scale-up reactions and synthetic transformations of the products.

Efficient Synthesis of 3,4-Disubstituted 7-Azaindoles Employing SEM as a Dual Protecting–Activating Group

Synlett ◽  
2019 ◽  
Vol 30 (20) ◽  
pp. 2273-2278 ◽  
Author(s):  
Piroska Gyárfás ◽  
János Gerencsér ◽  
Warren S. Wade ◽  
László Ürögdi ◽  
Zoltán Novák ◽  
...  
Keyword(s):  
Functional Groups ◽  
Efficient Method ◽  
Reaction Times ◽  
Nucleophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Efficient Synthesis ◽  
Mild Conditions

An efficient method for nucleophilic aromatic substitution on 7-azaindoles has been developed. The reaction is facilitated by the unique dual influence of SEM as both protecting and activating group, permitting mild conditions and short reaction times that are compatible with sensitive functional groups. The method is suitable for the synthesis of a broad range of products, most notably ethers.

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