N,N-Dialkyl-N′-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part XII. Synthesis and Reactivity of the Pyrazolo[3,4-e][1,2,4]thiadiazine Ring System

2015 ◽  
Vol 68 (9) ◽  
pp. 1455 ◽  
Author(s):  
Rebecca E. Norman ◽  
Michael V. Perkins ◽  
Andris J. Liepa ◽  
Craig L. Francis
Keyword(s):  
Pyrazole Ring ◽  
Ring Expansion ◽  
Ring System ◽  
Heterocyclic Synthesis ◽  
Ethyl Bromoacetate

N,N-Dialkyl-N′-chlorosulfonyl chloroformamidines 1 reacted regioselectively with 1-substituted 5-aminopyrazoles 2 via a 1,3-CCN dinucleophilic substitution to afford pyrazolo[3,4-e][1,2,4]thiadiazines 3 as the sole isolated products. Compounds 3, representatives of a very rare ring system, were shown to possess three nucleophilic sites at N2, N4, and N6. Methylation occurred at all three sites. Alkylation with benzylic halides occurred preferentially at N2, but some also occurred at N4, and at C7a. Alkylation with ethyl bromoacetate occurred at both N4 and N6, but the latter derivatives underwent a pyrazole ring expansion to afford pyrimido[4,5-e][1,2,4]thiadiazine derivatives. Compounds 3 were unreactive towards various acylating agents.

N,N-Dialkyl-N′-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part XI. Some Substitution Reactions of Pyrazolo[1,5-b][1,2,4,6]thiatriazine 1,1-Dioxides

2015 ◽  
Vol 68 (7) ◽  
pp. 1011 ◽  
Author(s):  
Rebecca E. Norman ◽  
Michael V. Perkins ◽  
Andris J. Liepa ◽  
Craig L. Francis
Keyword(s):  
Sulfur Dioxide ◽  
Pyrazole Ring ◽  
Ring Expansion ◽  
Heterocyclic Synthesis ◽  
Substitution Reactions

The recently discovered pyrazolo[1,5-b][1,2,4,6]thiatriazine template was shown to possess four nucleophilic sites (N2, N4, C5, N7) that underwent a range of substitution reactions. Methylation occurred at both N4 and N7. Alkylation with benzylic halides occurred preferentially at N7, regardless of the solvent, but also occurred at C5, N4, and N2. Similar alkylation with α-halo esters occurred at both N4 and N7, but the latter derivatives underwent a novel pyrazole ring expansion to afford pyrimido[1,6-b][1,2,4,6]thiatriazine derivatives. Bromination of pyrazolo[1,5-b][1,2,4,6]thiatriazines afforded unstable 5-bromo derivatives. Tosylation occurred selectively at C5, but in modest yield; catalysis with 1-methylimidazole also led to a low yield of the 5,5′-dimer. The action of HCl on N7-benzylated pyrazolo[1,5-b][1,2,4,6]thiatriazines readily caused extrusion of sulfur dioxide to produce pyrazolo-guanidines.

scholarly journals Crystal structure of (Z)-1-(3,4-dichlorophenyl)-3-methyl-4-[(naphthalen-1-ylamino)(p-tolyl)methylidene]-1H-pyrazol-5(4H)-one

2014 ◽  
Vol 70 (9) ◽  
pp. o955-o956 ◽  
Author(s):  
Naresh Sharma ◽  
Sanjay Parihar ◽  
R. N. Jadeja ◽  
Rajni Kant ◽  
Vivek K. Gupta
Keyword(s):  
Benzene Ring ◽  
Three Dimensional ◽  
Pyrazole Ring ◽  
Carbonyl Oxygen ◽  
Ring System ◽  
Dimensional Structure ◽  
Naphthalene Ring ◽  
Compound C ◽  
Schiff Base Compound ◽  
Base Compound

The title Schiff base compound, C28H21Cl2N3O, was synthesized by the condensation of 1-(3,4-dichlorophenyl)-3-methyl-4-(4-methylbenzoyl)-1H-pyrazol-5(4H)-one with 1-aminonaphthalene. Thep-tolyl ring is normal to the pyrazole ring, with a dihedral angle of 88.02 (14)°, and inclined to the naphthalene ring system by 78.60 (12)°. The pyrazole ring is inclined to the naphthalene ring system and the dichloro-substituted benzene ring by 63.30 (12) and 11.03 (13)°, respectively. The amino group and carbonyl oxygen atom are involved in an intramolecular N—H...O hydrogen bond enclosing anS(6) ring motif. There is also a short C—H...O contact involving the carbonyl O atom and the adjacent benzene ring. In the crystal, molecules are linked by C—H...π interactions, forming a three-dimensional structure.

scholarly journals 6-Amino-3-methyl-4-(3,4,5-trimethoxyphenyl)-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile

2014 ◽  
Vol 70 (8) ◽  
pp. o875-o876 ◽  
Author(s):  
Naresh Sharma ◽  
Goutam Brahmachari ◽  
Bubun Banerjee ◽  
Rajni Kant ◽  
Vivek K. Gupta
Keyword(s):  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Title Compound ◽  
Pyrazole Ring ◽  
Ring System ◽  
Boat Conformation ◽  
Two Dimensional ◽  
Compound C ◽  
Dimensional Network ◽  
Centroid Distance

In the title compound, C17H18N4O4, the dihedral angle between the benzene ring and 2,4-dihydropyrano[2,3-c]pyrazole ring system is 89.41 (7)°. The pyran moiety adopts a strongly flattened boat conformation. In the crystal, molecules are linked by N—H...N, N—H...O, C—H...N and C—H...O hydrogen bonds into an infinite two-dimensional network parallel to (110). There are π–π interactions between the pyrazole rings in neighbouring layers [centroid–centroid distance = 3.621 (1) Å].

Synthetic studies related to mycobactins. III. Approaches to the synthesis of the cobactin ring system

1972 ◽  
Vol 25 (11) ◽  
pp. 2429 ◽  
Author(s):  
DSC Black ◽  
RFC Brown ◽  
AM Wade
Keyword(s):  
Primary Amine ◽  
Ring Expansion ◽  
Hydroxamic Acids ◽  
Ring System ◽  
Ethyl Benzoate ◽  
Yield Reduction ◽  
Similar Reaction ◽  
Oxidation Reactions ◽  
Cyclic Hydroxamic Acids ◽  
Synthetic Studies

The synthesis of several seven-membered cyclic hydroxamic acids has been carried out in low yield. Reduction of diethyl 2-hydroxyiminoheptane-l,7-dioate afforded ethyl 1-hydroxy-7-oxohexahydroazepine-2-carboxylate, together with related acyclic products. The cobactin precursor 3-bromo-1-hydroxyhexahydro-azepin-2-one was obtained by the ring expansion of 2-bromocyclohexanone with benzenesulphonohydroxamic acid and also by the peracid oxidation of 6-bromo-7-ethoxy-3,4,5,6-tetrahydro-2H-azepine. The methyl and cinnamyl imidates of hexanolactam were oxidized by peracid to 1-hydroxyhexahydroazepin-2-one, in addition to the related imino- and nitroso-hexanoic esters. In a similar reaction, 1-hydroxypiperidin-2-one was obtained from 2-methoxy-3,4,5,6-tetrahydropyridine. During the course of these oxidation reactions, the intermediate oxaziridines 7-methoxy-8-oxa-1-azabicyclo[5,1,0]octane and 6-bromo-7-ethoxy-8-oxa-1-azabicyclo[5,1,0]octane were isolated and identified. The peraoid oxidation of ethyl N-cyclohexylbenzimidate yielded cyclohexylhydroxylamine and ethyl benzoate in reasonable yields. This reaction suggests a useful method for the conversion of a primary amine into the related hydroxylamine.

scholarly journals 1-[2,6-Dichloro-4-(trifluoromethyl)phenyl]-3,4-dimethylpyrano[2,3-c]pyrazol-6(1H)-one

2012 ◽  
Vol 68 (8) ◽  
pp. o2350-o2350
Author(s):  
Hoong-Kun Fun ◽  
Wan-Sin Loh ◽  
B. K. Sarojini ◽  
B. J. Mohan ◽  
B. Narayana
Keyword(s):  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Dihedral Angle ◽  
Title Compound ◽  
Pyrazole Ring ◽  
Ring System ◽  
Helical Chain ◽  
Maximum Deviation ◽  
Compound C

In the title compound, C15H9Cl2F3N2O2, the 1,6-dihydropyrano[2,3-c]pyrazole ring system is almost planar, with a maximum deviation of 0.0226 (14) Å, and forms a dihedral angle of 69.90 (6)° with the benzene ring. In the crystal, molecules are linked into a helical chain along thecaxis by C—H...O hydrogen bonds.

N,N-Dialkyl-N′-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part XIV. Synthesis and Reactivity of the New Benzo[4,5]imidazo[1,2-b][1,2,6]thiadiazine Ring System

2018 ◽  
Vol 71 (1) ◽  
pp. 58 ◽  
Author(s):  
Dylan Innes ◽  
Michael V. Perkins ◽  
Andris J. Liepa ◽  
Craig L. Francis
Keyword(s):  
Medicinal Chemistry ◽  
Ring System ◽  
Heterocyclic Synthesis ◽  
Alkyl Derivatives ◽  
Regioselective Reactions ◽  
Novel Scaffold ◽  
Derivatives Of ◽  
Related Compounds

N,N-Dialkyl-N′-chlorosulfonyl chloroformamidines 1 underwent regioselective reactions with the 1,3-NCC bis-nucleophilic 1H-benzimidazole-2-acetonitriles 4 and related compounds to produce benzo[4,5]imidazo[1,2-b][1,2,6]thiadiazine dioxides 6, 9, 12, and 14, representatives of a new ring system. Reaction of dichlorides 1 with trifluoroacetyl derivative 16 afforded benzo[4,5]imidazo[1,2-c]pyrimidines 19 and 20. An N-acyl and some N-alkyl derivatives of benzimidazo-thiadiazines 6 were prepared to demonstrate the potential of this new ring system as a novel scaffold for synthetic and medicinal chemistry applications. Treatment of the 4-cyano-5-methyl-benzimidazo-thiadiazine 26c with LiAlH4 resulted in an unexpected and remarkable conversion of the nitrile to give the 4,5-dimethyl-benzimidazo-thiadiazine 29.

The Meisenheimer Rearrangement in Heterocyclic Synthesis. IV. Derivatives of the 2H,6H-1,5,4-Benzodioxazocine and 7H-1,6,5-Benzodioxazonine Ring Systems: X-Ray Crystal Structure of 10-Methoxy-5-methyl-7-phenyl-2,3,4,5-tetrahydro-7H-1,6,5-benzodioxazonine

1988 ◽  
Vol 41 (3) ◽  
pp. 293 ◽  
Author(s):  
JB Bremner ◽  
EJ Browne ◽  
LM Engelhardt ◽  
IWK Gunawardana ◽  
AH White
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Crystal And Molecular Structure ◽  
Ring System ◽  
Heterocyclic Synthesis ◽  
Rearrangement Product ◽  
Ring Systems ◽  
X Ray ◽  
Derivatives Of ◽  
Moderate Yield

Meisenheimer rearrangement of the N-oxides (4) derived from a series of 5-aryl-4-methyl-2,3,4,5-tetrahydro-1,4-benzoxazepines (3) gave rise to eight derivatives (5) of the new 2H,6H-1,5,4-benzodioxazocine ring system. Reaction of 9-methoxy-5-methyl-6-phenyl-3,4,5,6- tetrahydro-2H-1,5-benzoxazocine (6) with 3-chloroperoxybenzoic acid gave an unstable N-oxide (7). A Meisenheimer rearrangement product from (7), 10-methoxy-5-methyl-7-phenyl-2,3,4,5-tetrahydro-7 H-1,6,5- benzodioxazonine (8), the first example of this ring system, was isolated directly in moderate yield on oxidation of (6) with cooling. The crystal and molecular structure of (8) has been determined by X-ray crystallographic methods.

Claisen Ring Expansion Approach toward the CDEF Ring System of Lancifodilactone G

Heterocycles ◽  
2009 ◽  
Vol 79 (1) ◽  
pp. 299 ◽  
Author(s):  
Leo A. Paquette ◽  
Kwong Wah Lai
Keyword(s):  
Ring Expansion ◽  
Ring System
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