Carbon–nitrogen bond cleavage of pyridine with two molecular substituted allenoates: access to 2-arylpyrimidin-4(3H)-one

2018 ◽  
Vol 54 (100) ◽  
pp. 14128-14131 ◽  
Author(s):  
Tao Jin ◽  
Hongdong Yuan ◽  
Shikuan Su ◽  
Xueshun Jia ◽  
Chunju Li ◽  
...  
Keyword(s):  
Benzene Ring ◽  
Ring Opening ◽  
Pyridine Ring ◽  
Bond Cleavage ◽  
Ring System ◽  
Nitrogen Bond

A DABCO-catalyzed annulation reaction of pyridin-2-amine and substituted allenoates enables the ring-opening of a pyridine ring system and the formation of two new rings including a pyrimidinone ring and a benzene ring.

scholarly journals 6-(1H-Indol-3-yl)-4-phenyl-2,2′-bipyridine-5-carbonitrile

2009 ◽  
Vol 65 (6) ◽  
pp. o1187-o1187 ◽  
Author(s):  
Weijun Zhu ◽  
Yan Xiang ◽  
Songlei Zhu
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Dihedral Angle ◽  
Title Compound ◽  
Pyridine Ring ◽  
Ring System ◽  
Indole Ring ◽  
Compound C ◽  
Centrosymmetric Dimers

In the molecule of the title compound, C25H16N4, the pyridine rings are oriented at a dihedral angle of 0.92 (3)°, while the dihedral angle between the benzene ring and the adjacent pyridine ring is 56.51 (3)°. In the crystal structure, intermolecular N—H...N hydrogen bonds link the molecules into centrosymmetric dimers, formingR22(16) ring motifs. π–π contacts between the pyridine ring and the indole ring system and between the pyridine rings [centroid–centroid distances = 3.923 (2) and 3.724 (2) Å] may further stabilize the structure. Two weak C—H...π interactions are also present.

scholarly journals Crystal structure and Hirshfeld surface analysis of 4-allyl-6-bromo-2-(4-chlorophenyl)-4H-imidazo[4,5-b]pyridine

2019 ◽  
Vol 75 (1) ◽  
pp. 43-48
Author(s):  
Selma Bourichi ◽  
Youssef Kandri Rodi ◽  
Tuncer Hökelek ◽  
Amal Haoudi ◽  
Catherine Renard ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Title Compound ◽  
Pyridine Ring ◽  
Ring System ◽  
Hirshfeld Surface ◽  
Stacking Interactions ◽  
Compound C ◽  
Ring Motif

The title compound, C15H11BrClN3, is built up from a planar imidazo[4,5-b]pyridine unit linked to phenyl and allyl substituents. The allyl substituent is rotated significantly out of the imidazo[4,5-b]pyridine plane, while the benzene ring is inclined by 3.84 (6)° to the ring system. In the crystal, molecules are linked via a pair of weak intermolecular C—H...N hydrogen bonds, forming an inversion dimer with an R 2 2(20) ring motif. The dimers are further connected by π–π stacking interactions between the imidazo[4,5-b]pyridine ring systems [centroid–centroid distances = 3.7161 (13) and 3.8478 (13) Å]. The important contributions to the Hirshfeld surface are H...H (35.9%), H...Cl/Cl...H (15.0%), H...C/C...H (12.4%), H...Br/Br...H (10.8%), H...N/N...H (7.5%), C...Br/Br...C (5.9%), C...C (5.5%) and C...N/N...C (4.0%) contacts.

scholarly journals (E)-3-[4-(Benzo[d]oxazol-2-yl)styryl]-1-methylpyridin-1-ium hexafluoridophosphate

IUCrData ◽  
2017 ◽  
Vol 2 (12) ◽  
Author(s):  
Hong-Kang Xu ◽  
Lin Kong ◽  
Fei Li
Keyword(s):  
Hydrogen Bond ◽  
Benzene Ring ◽  
Pyridine Ring ◽  
Ion Pair ◽  
Ring System ◽  
Dihedral Angles ◽  
Molecular Salt

In the cation of the title molecular salt, C21H17N2O+·PF6−, the pyridine ring and benzoxazole ring system are twisted with respect to the central benzene ring at dihedral angles of 23.75 (18) and 5.53 (16)°. In the crystal, the hexafluoridophosphate anion accepts a weak C—H...F hydrogen bond from the cation to form an ion-pair.

scholarly journals 7-Diethylamino-3-{(E)-4-[(E)-2-(pyridin-4-yl)ethenyl]styryl}-2H-chromen-2-one

2014 ◽  
Vol 70 (2) ◽  
pp. o176-o176
Author(s):  
Li-Ping Zhou ◽  
Ling-Liang Long
Keyword(s):  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Pyridine Ring ◽  
Three Dimensional ◽  
Coumarin Derivative ◽  
Ring System ◽  
Dihedral Angles ◽  
Maximum Deviation ◽  
Supramolecular Architecture ◽  
Coumarin Ring

In the title coumarin derivative, C28H26N2O2, the coumarin unit is approximately planar, with a maximum deviation of 0.048 (3) Å. The central benzene ring is oriented at dihedral angles of 30.15 (14) and 10.51 (11)°, respectively, to the pyridine ring and coumarin ring system. In the crystal, weak C—H...O and C—H...N hydrogen bonds and weak C—H...π interactions link the molecules into a three-dimensional supramolecular architecture.

scholarly journals An α/β-hydrolase fold protein in the biosynthesis of thiostrepton exhibits a dual activity for endopeptidyl hydrolysis and epoxide ring opening/macrocyclization

2016 ◽  
Vol 113 (50) ◽  
pp. 14318-14323 ◽  
Author(s):  
Qingfei Zheng ◽  
Shoufeng Wang ◽  
Panpan Duan ◽  
Rijing Liao ◽  
Dandan Chen ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Ring Opening ◽  
Bond Cleavage ◽  
Catalytic Triad ◽  
Ring System ◽  
Leader Peptide ◽  
Epoxide Ring ◽  
Unexpected Finding ◽  
Epoxide Ring Opening ◽  
Hydrolase Fold

Thiostrepton (TSR), an archetypal bimacrocyclic thiopeptide antibiotic that arises from complex posttranslational modifications of a genetically encoded precursor peptide, possesses a quinaldic acid (QA) moiety within the side-ring system of a thiopeptide-characteristic framework. Focusing on selective engineering of the QA moiety, i.e., by fluorination or methylation, we have recently designed and biosynthesized biologically more active TSR analogs. Using these analogs as chemical probes, we uncovered an unusual indirect mechanism of TSR-type thiopeptides, which are able to act against intracellular pathogens through host autophagy induction in addition to direct targeting of bacterial ribosome. Herein, we report the accumulation of 6′-fluoro-7′, 8′-epoxy-TSR, a key intermediate in the preparation of the analog 6′-fluoro-TSR. This unexpected finding led to unveiling of the TSR maturation process, which involves an unusual dual activity of TsrI, an α/β-hydrolase fold protein, for cascade C-N bond cleavage and formation during side-ring system construction. These two functions of TsrI rely on the same catalytic triad, Ser72-His200-Asp191, which first mediates endopeptidyl hydrolysis that occurs selectively between the residues Met-1 and Ile1 for removal of the leader peptide and then triggers epoxide ring opening for closure of the QA-containing side-ring system in a regio- and stereo-specific manner. The former reaction likely requires the formation of an acyl-Ser72 enzyme intermediate; in contrast, the latter is independent of Ser72. Consequently, C-6′ fluorination of QA lowers the reactivity of the epoxide intermediate and, thereby, allows the dissection of the TsrI-associated enzymatic process that proceeds rapidly and typically is difficult to be realized during TSR biosynthesis.

Resolving the Mystery of Ring Opening in the Synthesis of Benzo[d][1, 3]oxazin-4-one and Quinazolin-4(3H)-one

2019 ◽  
Vol 16 (11) ◽  
pp. 898-905
Author(s):  
Harun Patel ◽  
Rahul Pawara ◽  
Sanjay Surana
Keyword(s):  
Characteristic Feature ◽  
Ring Opening ◽  
Biological Activities ◽  
Heterocyclic Ring ◽  
Ring System ◽  
Time Saving ◽  
Fusion Strategy ◽  
Good Template ◽  
Lead Generation

Quinazoline is the six-membered heterocyclic ring system reported for its versatile biological activities. This characteristic feature of quinazoline makes it a good template for a lead generation library. Ring opening is one of the major concerns in the synthesis of quinazolin-4(3H)-one that results in diamide formation. Here, alternative fusion strategy is reported, which is a time-saving and costeffective method to overcome the ring opening problem associated with the synthesis of benzo[ d][1,3]oxazin-4-one and quinazolin-4(3H)-one.

ChemInform Abstract: Iron-Catalyzed Synthesis of Glycine Derivatives via Carbon-Nitrogen Bond Cleavage Using Diazoacetate.

ChemInform ◽  
2011 ◽  
Vol 42 (14) ◽  
pp. no-no
Author(s):  
Yoichiro Kuninobu ◽  
Mitsumi Nishi ◽  
Kazuhiko Takai
Keyword(s):  
Bond Cleavage ◽  
Glycine Derivatives ◽  
Nitrogen Bond
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