Cyclophanes. VI. The synthesis of [2,2](3,3')biphenylparacyclophanedienes

1976 ◽  
Vol 29 (6) ◽  
pp. 1267 ◽  
Author(s):  
PJ Jessup ◽  
JA Reiss
Keyword(s):  
Ring Opening ◽  
Ring System ◽  
Ring Contraction ◽  
Stevens Rearrangement ◽  
Ring Opening Reaction ◽  
Disubstituted Benzene ◽  
Contraction Procedure

The preparations of [2,2](3,3')biphenylparacyclophane-1,9-dine (19) and a dimethyl derivative (20) synthesized by a ring-contraction procedure of the corresponding dithiacyclophanes (11) and (12) are reported. Both dienes (19) and (20) photocyclized under oxidative conditions to the benzo[ghi]- perylenes (21) and (22). Difficulties associated with the Stevens rearrangement in cyclophanes containing a para-disubstituted benzene moiety have been rationalized in terms of a competing ring- opening reaction. Several other reactions of the biphenylparacylophane ring system are reported, and the stereochemistry of the macrocycle is discussed.

Cyclophanes. IV. Synthetic approaches to cyclophane dienes. The preparation of [2,2](2,7)Naphthalenophane-1,11-diene

1976 ◽  
Vol 29 (1) ◽  
pp. 163 ◽  
Author(s):  
JR Davy ◽  
JA Reiss
Keyword(s):  
Ring System ◽  
Ring Contraction ◽  
Stevens Rearrangement ◽  
Elimination Procedure ◽  
Synthetic Approaches ◽  
Hofmann Elimination

The synthesis of [2,2](2,7)naphthalenophane-1,ll-diene (2a) from 2,13-dithia[3,3](2,7)naphthalenophane (4) by means of a Stevens rearrangement ring contraction and a Hofmann elimination procedure is described. The diene was found to undergo an efficient oxidative photochemical cyclization to coronene. Several other reactions of the naphthalenophane ring system are described, and the stereochemistry of the macrocycle is discussed.

Synthetic Studies on Cyclocitrinol: Construction of the ABC Ring System Based on Epoxy-Nitrile Cyclization

Synlett ◽  
2020 ◽  
Author(s):  
Kazuto Sato ◽  
Keiji Tanino
Keyword(s):  
Intramolecular Cyclization ◽  
Ring Opening ◽  
Model Compound ◽  
Stereoselective Synthesis ◽  
Ring System ◽  
Cyclization Reaction ◽  
Ring Opening Reaction ◽  
Synthetic Studies ◽  
Highly Strained

The stereoselective synthesis of a model compound containing the ABC ring system of cyclocitrinol was accomplished. After connecting a C-ring allyltitanium segment with an A ring bicyclo[4.1.0]heptanone segment, the seven-membered B ring moiety was constructed by an intramolecular cyclization reaction of an epoxy nitrile. The enone moiety was introduced through an oxidative decyanation reaction, and the bicyclo[4.4.1]undecane skeleton with the highly strained olefin moiety was formed through a ring-opening reaction of the bicyclo[4.1.0]heptane substructure.

On the Conrotatory Ring Opening of 3-Carbomethoxycyclobutene Vis-À-Vis 3-Carbomethoxy-1,2-Benzocyclobutene and the Predominant Inward Opening of 3-Dimethylaminocarbonyl-1,2-Benzocyclobutene

2018 ◽  
Author(s):  
Veejendra Yadav ◽  
Dasari L V K Prasad ◽  
Arpita Yadav ◽  
Maddali L N Rao
Keyword(s):  
Transition State ◽  
Ring Opening ◽  
Electron Process ◽  
Ring Opening Reaction ◽  
Stable Species ◽  
Electron Event

<p>The torquoselectivity of conrotatory ring opening of 3-carbomethoxycyclobutene is controlled by p<sub>C1C2</sub>→s*<sub>C3C4</sub> and s<sub>C3C4</sub>→p*<sub>CO</sub> interactions in the transition state in a 4-electron process as opposed to only s<sub>C3C4</sub>→p*<sub>CO</sub> interaction in an apparently 8-electron event in 3-carbomethoxy-1,2-benzocyclobutene. The ring opening of 3-carbomethoxy-1,2-benzocyclobutene is sufficiently endothermic. We therefore argue that the reverse ring closing reaction is faster than the forward ring opening reaction and, thus, it establishes an equilibrium between the two and subsequently allows formation of the more stable species <i>via</i> outward ring opening reaction. Application of this argument to 3-dimethylaminocarbonyl-1,2-benzocyclobutene explains the predominantly observed inward opening.</p>

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.

scholarly journals Expanding Monomers as Anti-Shrinkage Additives

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 806
Author(s):  
Philipp Marx ◽  
Frank Wiesbrock
Keyword(s):  
Ring Opening ◽  
Covalent Bond ◽  
Volumetric Shrinkage ◽  
Structure Property ◽  
Atomic Packing ◽  
Materials Properties ◽  
Volumetric Expansion ◽  
Structure Property Relationships ◽  
Ring Opening Reaction ◽  
Measuring Techniques

Commonly, volumetric shrinkage occurs during polymerizations due to the shortening of the equilibrium Van der Waals distance of two molecules to the length of a (significantly shorter) covalent bond. This volumetric shrinkage can have severe influence on the materials’ properties. One strategy to overcome this volumetric shrinkage is the use of expanding monomers that show volumetric expansion during polymerization reactions. Such monomers exhibit cyclic or even oligocyclic structural motifs with a correspondingly dense atomic packing. During the ring-opening reaction of such monomers, linear structures with atomic packing of lower density are formed, which results in volumetric expansion or at least reduced volumetric shrinkage. This review provides a concise overview of expanding monomers with a focus on the elucidation of structure-property relationships. Preceded by a brief introduction of measuring techniques for the quantification of volumetric changes, the most prominent classes of expanding monomers will be presented and discussed, namely cycloalkanes and cycloalkenes, oxacycles, benzoxazines, as well as thiocyclic compounds. Spiroorthoesters, spiroorthocarbonates, cyclic carbonates, and benzoxazines are particularly highlighted.

Design and synthesis of 1,8-Naphthalimide Functionalized Benzothiadiazoles

2021 ◽  
Author(s):  
Rajneesh Misra ◽  
Yogjivan Rout
Keyword(s):  
Ring Opening ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Design And Synthesis ◽  
Cross Coupling Reaction ◽  
Ring Opening Reaction

A series of multi acceptor based push-pull derivatives BTD2–BTD5 were designed and synthesized via Pd-catalyzed Sonogashira cross-coupling reaction followed by [2+2] cycloaddition–electrocyclic ring-opening reaction in which benzothiadiazole (BTD, A1), naphthalimide...

N-Chlorinative Ring Contraction of 1,4-Dimethoxyphthalazines via a Bicyclization/Ring-Opening Mechanism

Synthesis ◽  
2020 ◽  
Author(s):  
Jeong Kyun Im ◽  
Ilju Jeong ◽  
Jun-Ho Choi ◽  
Won-jin Chung ◽  
ByeongDo Yang ◽  
...  
Keyword(s):  
Ring Opening ◽  
Reaction Conditions ◽  
Ring Contraction ◽  
Silyl Group ◽  
Favorskii Rearrangement ◽  
Mechanistic Analysis ◽  
Group A ◽  
Overall Efficiency ◽  
Trichloroisocyanuric Acid

AbstractAn unprecedented N-chlorinative ring contraction of 1,2-diazines was discovered and investigated with an electrophilic chlorinating reagent, trichloroisocyanuric acid (TCICA). Through optimization and mechanistic analysis, the assisting role of n-Bu4NCl as an exogenous nucleophile was identified, and the optimized reaction conditions were applied to a range of 1,4-dimethoxyphthalazine derivatives. Also, an improvement of overall efficiency was demonstrated by the use of a labile O-silyl group. A bicyclization/ring-opening mechanism, inspired by the Favorskii rearrangement, was proposed and supported by the DFT calculations. Furthermore, the efforts on scope expansion as well as the evaluation of other electrophilic promoters revealed that the newly developed ring contraction reactivity is a unique characteristic of 1,4-dimethoxyphthalazine scaffold and TCICA.

scholarly journals (1R,4S,5S)-5-((3-Hydroxypropyl)amino)-4-((1-Methyl-1H-tetrazol-5-yl)thio)Cyclopent-2-en-1-ol

Molbank ◽  
10.3390/m1199 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1199
Author(s):  
Milene A. G. Fortunato ◽  
Filipa Siopa ◽  
Carlos A. M. Afonso
Keyword(s):  
Spectral Data ◽  
13C Nmr ◽  
Ring Opening ◽  
Environmentally Friendly ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
Excellent Yield ◽  
Ring Opening Reaction ◽  
Nucleophilic Ring Opening

Using environmentally friendly conditions, the nucleophilic ring-opening reaction of 6-azabicyclo[3.1.0]hex-3-en-2-ol with 1-methyl-1H-tetrazole-5-thiol provided a novel thiol-incorporated aminocyclopentitol, (1R,4S,5S)-5-((3-hydroxypropyl)amino)-4-((1-methyl-1H-tetrazol-5-yl)thio)cyclopent-2-en-1-ol, in excellent yield (95%). The newly synthesized compound was analyzed and characterized via 1H, 13C-NMR, HSQC, and mass spectral data.

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