Acid-Catalyzed Ring-expansion of 4-(1-hydroxycyclobutyl)-1,2,3-triazoles

2022 ◽  
Author(s):  
Mingchuan Xu ◽  
Lei Liu ◽  
Tao Wang ◽  
Han Luo ◽  
Meili Hou ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Expansion ◽  
Rearrangement Reaction ◽  
Acid Catalyzed ◽  
Semipinacol Rearrangement

We here reported a direct ring-opening/semipinacol rearrangement reaction of 4-(1-hydroxycyclobutyl)-1,2,3-triazole, in which N-acyl substituted 1,2,3-triazole was generated in situ and would trigger thermodynamically controlled electrocyclization ring-opening to afford rearrangement precursor...

Ring expansion and ring opening of 3-halooxindoles with N-alkoxycarbonyl-O-tosylhydroxylamines for divergent access to 4-aminoquinolin-2-ones and N-Cbz-N’-arylureas

2021 ◽  
Author(s):  
Wei-Cheng Yuan ◽  
Jian Zuo ◽  
Shu-Pei Yuan ◽  
Jian-Qiang Zhao ◽  
Zhen-Hua Wang ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Expansion

The reaction of N-alkoxycarbonyl-O-tosylhydroxylamines with indol-2-ones in situ generated from 3-halooxindoles has been developed for divergently accessing 4-aminoquinolin-2-ones and N-Cbz-N’-arylureas in good to excellent yields.

Synthesis of functionalized pyrazole derivatives by regioselective [3+2] cycloadditions of N-Boc-α-amino acid-derived ynones

2018 ◽  
Vol 73 (7) ◽  
pp. 467-480 ◽  
Author(s):  
Eva Pušavec Kirar ◽  
Uroš Grošelj ◽  
Amalija Golobič ◽  
Franc Požgan ◽  
Sebastijan Ričko ◽  
...  
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Amino Acid ◽  
Ring Opening ◽  
Pyrazole Derivatives ◽  
X Ray Diffraction ◽  
X Ray ◽  
Acid Catalyzed ◽  
Azomethine Imines

Abstract [3+2] cycloadditions of ynones derived from glycine and (S)-alanine and some other dipolarophiles with azomethine imines, nitrile oxides, diazoacetate, and azidoacetate were studied. The dipolarophiles were obtained from α-amino acids, either by the reduction of the carboxy function with ethynylmagnesium bromide or by propiolation of the amino function. Cu-catalyzed cycloadditions of ynones to azomethine imines were regioselective and gave the expected cycloadducts as inseparable mixtures of diastereomers. In some instances, further oxidative hydrolytic ring-opening took place to afford 3,3-dimethyl-3-(1H-pyrazol-1-yl)propanoic acids. Acid-catalyzed cycloadditions of 3-butenone were also regioselective and provided mixtures of diastereomeric cycloadducts, which were separated by chromatography. In the reactions of title ynones with alkyl diazoacetates, in situ-formed benzonitrile oxides, and tert-butyl azidoacetate, all cycloadducts were obtained as single regioisomers. The structures of all novel compounds were established by nuclear magnetic resonance and X-ray diffraction.

scholarly journals Synthesis of new tricyclic 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepine derivatives by [3+ + 2]-cycloaddition/rearrangement reactions

2018 ◽  
Vol 14 ◽  
pp. 1826-1833 ◽  
Author(s):  
Lin-bo Luan ◽  
Zi-jie Song ◽  
Zhi-ming Li ◽  
Quan-rui Wang
Keyword(s):  
Cycloaddition Reaction ◽  
Ring Expansion ◽  
Aluminium Chloride ◽  
Phenyl Substituent ◽  
Rearrangement Reaction ◽  
Rearrangement Reactions

Two new series of tricyclic heterocycles, namely 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepinium salts 10 and the related neutral, free bases 13 were synthesized from 4-acetoxy-1-acetyl-4-phenylazo-1,2,3,4-tetrahydroquinolines 8 and nitriles 9 in the presence of aluminium chloride by the [3+ + 2]-cycloaddition reaction of the in situ generated azocarbenium intermediates 14 followed by a ring-expansion rearrangement. In the rearrangement reaction, the phenyl substituent in the initially formed spiro-triazolium adducts 16 underwent a [1,2]-migration from C(3) to the electron-deficient N(2). This led to the ring expansion from 6-membered piperidine to 7-membered diazepine furnishing the tricyclic 1,2,4-triazole-fused 1,4-benzodiazepines.

Synthesis and Applications of Cyclopropanones and their Equivalents as Three-Carbon Building Blocks in Organic Synthesis

Synthesis ◽  
2021 ◽  
Author(s):  
Yujin Jang ◽  
Roger Machin-Rivera ◽  
Vincent Lindsay
Keyword(s):  
Organic Synthesis ◽  
Ring Opening ◽  
Building Blocks ◽  
Ring Expansion ◽  
Ring System ◽  
Small Ring ◽  
Future Directions ◽  
Highly Strained ◽  
And Storage

Cyclopropanone derivatives constitute highly strained cycloalkanones with promising applications as three-carbon building blocks in organic synthesis. Due to the presence of a ketone in such a small ring system, all C–C bonds and the carbonyl group are considered to be labile in suitable conditions, leading to a wide variety of synthetic disconnections, including nucleophilic addition, ring expansion, ring-opening and (formal) cycloaddition. Despite their synthetic potential, the widespread adoption of cyclopropanones as substrates has been considerably hampered by the difficulties associated with the preparation and storage of such unstable compounds, prompting the development of cyclopropanone surrogates that can equilibrate to parent ketone in situ via elimination. This review summarizes the syntheses and applications of cyclopropanone derivatives and their equivalents, and offers a perspective of the state of the field as well as its expected future directions.

scholarly journals On the Thermodynamic Control of Ring Opening of 4-Substituted 1,3,3-Tris-Carbethoxycyclobutene and the Role of the C-3 Substituent in Masking the Kinetic Torquoselectivity. An alternate reaction pathway

2021 ◽  
Author(s):  
Veejendra Yadav ◽  
Dasari L V K Prasad ◽  
Arpita Yadav ◽  
Maddali L N Rao
Keyword(s):  
Lewis Acid ◽  
Ring Opening ◽  
Reaction Pathway ◽  
Chloride Ion ◽  
Thermodynamic Control ◽  
Heterolytic Cleavage ◽  
Acid Catalyzed ◽  
Halogen Acid

<p>The predominant transformations of 4-methyl- and 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutenes to s-<i>trans</i>-<i>trans</i>-1,1,3-<i>tris</i>-carbethoxy-4-methyl- and 4-phenyl-1,3-butadienes, respectively, proceed through pathways entailing heterolytic cleavage of the s<sub>C3C4</sub> bond rather than the usual four-electron conrotatory ring opening following the rules of torquoselectivity. The adventitious or in situ generated halogen acid from CDCl<sub>3</sub> catalyzes the reaction of 4-methyl-1,3,3-<i>tris</i>-carbethoxycyclobutene by protonation of one of the two ester groups on C3 and, thereby, weakening the s<sub>C3C4</sub> bond to allow its heterolytic S<sub>N</sub>2 cleavage by the chloride ion. This is followed by <i>cisoid</i><b>→</b><i>transoid</i> isomerization and loss of the elements of the halogen acid to form the products. In the Lewis acid-catalyzed reaction of 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutene in CH<sub>2</sub>Cl<sub>2</sub>, coordination of the Lewis acid with one of two ester groups on C3 is followed by heterolytic cleavage of the s<sub>C3C4</sub> bond. The resultant species subsequently undergoes <i>cisoid</i><b>→</b><i>transoid</i> isomerization before losing the Lewis acid to form the products.<br></p>

scholarly journals On the Thermodynamic Control of Ring Opening of 4-Substituted 1,3,3-Tris-Carbethoxycyclobutene and the Role of the C-3 Substituent in Masking the Kinetic Torquoselectivity

2020 ◽  
Author(s):  
Veejendra Yadav ◽  
Dasari L V K Prasad ◽  
Arpita Yadav ◽  
Maddali L N Rao
Keyword(s):  
Lewis Acid ◽  
Ring Opening ◽  
Chloride Ion ◽  
Thermodynamic Control ◽  
Heterolytic Cleavage ◽  
Acid Catalyzed ◽  
Halogen Acid

<p>The predominant transformations of 4-methyl- and 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutenes to s-<i>trans</i>-<i>trans</i>-1,1,3-<i>tris</i>-carbethoxy-4-methyl- and 4-phenyl-1,3-butadienes, respectively, proceed through pathways entailing heterolytic cleavage of the s<sub>C3C4</sub> bond rather than the usual four-electron conrotatory ring opening following the rules of torquoselectivity. The adventitious or in situ generated halogen acid from CDCl<sub>3</sub> catalyzes the reaction of 4-methyl-1,3,3-<i>tris</i>-carbethoxycyclobutene by protonation of one of the two ester groups on C3 and, thereby, weakening the s<sub>C3C4</sub> bond to allow its heterolytic S<sub>N</sub>2 cleavage by the chloride ion. This is followed by <i>cisoid</i><b>→</b><i>transoid</i> isomerization and loss of the elements of the halogen acid to form the products. In the Lewis acid-catalyzed reaction of 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutene in CH<sub>2</sub>Cl<sub>2</sub>, coordination of the Lewis acid with one of two ester groups on C3 is followed by heterolytic cleavage of the s<sub>C3C4</sub> bond. The resultant species subsequently undergoes <i>cisoid</i><b>→</b><i>transoid</i> isomerization before losing the Lewis acid to form the products.<br></p>

scholarly journals On the Thermodynamic Control of Ring Opening of 4-Substituted 1,3,3-Tris-Carbethoxycyclobutene and the Role of the C-3 Substituent in Masking the Kinetic Torquoselectivity. An alternate reaction pathway

2021 ◽  
Author(s):  
Veejendra Yadav ◽  
Dasari L V K Prasad ◽  
Arpita Yadav ◽  
Maddali L N Rao
Keyword(s):  
Lewis Acid ◽  
Ring Opening ◽  
Reaction Pathway ◽  
Chloride Ion ◽  
Ester Group ◽  
Heterolytic Cleavage ◽  
Acid Catalyzed ◽  
Halogen Acid

<p>The predominant transformations of 4-methyl- and 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutenes to s-<i>trans</i>,<i>trans</i>-1,1,3-<i>tris</i>-carbethoxy-4-methyl- and s-<i>trans</i>,<i>trans</i>-1,1,3-<i>tris</i>-carbethoxy-4-phenyl-1,3-butadienes, respectively, are discussed to proceed through pathways entailing heterolytic cleavage of the s<sub>C3C4</sub> bond rather than the usual conrotatory ring opening following the rules of torquoselectivity. The adventitious or in situ generated halogen acid from CDCl<sub>3</sub> catalyzes the reaction by protonation of the geminal ester group to weaken s<sub>C3C4</sub> bond and allow its S<sub>N</sub>2 cleavage by chloride ion. This is followed by cisoid<b>→</b>transoid isomerization and loss of the elements of halogen acid to form the products. In the Lewis acid-catalyzed reaction of 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutene in CH<sub>2</sub>Cl<sub>2</sub>, coordination of Lewis acid with the geminal ester group is followed by heterolytic cleavage of the s<sub>C3C4</sub> bond. The resultant species subsequently undergoes cisoid<b>→</b>transoid isomerization before losing the Lewis acid to form the products.<br></p>

scholarly journals On the Thermodynamic Control of Ring Opening of 4-Substituted 1,3,3-Tris-Carbethoxycyclobutene and the Role of the C-3 Substituent in Masking the Kinetic Torquoselectivity

2020 ◽  
Author(s):  
Veejendra Yadav ◽  
Dasari L V K Prasad ◽  
Arpita Yadav ◽  
Maddali L N Rao
Keyword(s):  
Lewis Acid ◽  
Ring Opening ◽  
Chloride Ion ◽  
Thermodynamic Control ◽  
Heterolytic Cleavage ◽  
Acid Catalyzed ◽  
Halogen Acid

<p>The predominant transformations of 4-methyl- and 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutenes to s-<i>trans</i>-<i>trans</i>-1,1,3-<i>tris</i>-carbethoxy-4-methyl- and 4-phenyl-1,3-butadienes, respectively, proceed through pathways entailing heterolytic cleavage of the s<sub>C3C4</sub> bond rather than the usual four-electron conrotatory ring opening following the rules of torquoselectivity. The adventitious or in situ generated halogen acid from CDCl<sub>3</sub> catalyzes the reaction of 4-methyl-1,3,3-<i>tris</i>-carbethoxycyclobutene by protonation of one of the two ester groups on C3 and, thereby, weakening the s<sub>C3C4</sub> bond to allow its heterolytic S<sub>N</sub>2 cleavage by the chloride ion. This is followed by <i>cisoid</i><b>→</b><i>transoid</i> isomerization and loss of the elements of the halogen acid to form the products. In the Lewis acid-catalyzed reaction of 4-phenyl-1,3,3-<i>tris</i>-carbethoxycyclobutene in CH<sub>2</sub>Cl<sub>2</sub>, coordination of the Lewis acid with one of two ester groups on C3 is followed by heterolytic cleavage of the s<sub>C3C4</sub> bond. The resultant species subsequently undergoes <i>cisoid</i><b>→</b><i>transoid</i> isomerization before losing the Lewis acid to form the products.<br></p>

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