scholarly journals Spiro annulation of cage polycycles via Grignard reaction and ring-closing metathesis as key steps

2015 ◽  
Vol 11 ◽  
pp. 1367-1372 ◽  
Author(s):  
Sambasivarao Kotha ◽  
Mohammad Saifuddin ◽  
Rashid Ali ◽  
Gaddamedi Sreevani
Keyword(s):  
Single Crystal ◽  
Diels Alder ◽  
Grignard Reaction ◽  
X Ray Diffraction ◽  
Ring Closing Metathesis ◽  
Cage Compounds ◽  
X Ray ◽  
Synthetic Strategy ◽  
Cage Compound ◽  
Key Steps

A simple synthetic strategy to C 2-symmetric bis-spiro-pyrano cage compound 7 involving ring-closing metathesis is reported. The hexacyclic dione 10 was prepared from simple and readily available starting materials such as 1,4-naphthoquinone and cyclopentadiene. The synthesis of an unprecedented octacyclic cage compound through intramolecular Diels–Alder (DA) reaction as a key step is described. The structures of three new cage compounds 7, 12 and 18 were confirmed by single crystal X-ray diffraction studies.

scholarly journals Bridgehead vicinal diallylation of norbornene derivatives and extension to propellane derivatives via ring-closing metathesis

2016 ◽  
Vol 12 ◽  
pp. 1877-1883 ◽  
Author(s):  
Sambasivarao Kotha ◽  
Rama Gunta
Keyword(s):  
Single Crystal ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
Ring Closing Metathesis ◽  
X Ray ◽  
Synthetic Strategy ◽  
Norbornene Derivatives

Here, we report a simple synthetic strategy to the bridgehead vicinal diallylation of norbornene derivatives. These substrates are useful to generate propellanes via ring-closing metathesis. Single-crystal X-ray diffraction analysis of four compounds led to the realization of configurational correction of earlier reported molecules.

Structural Study of an Unusual Diels-Alder Adduct

1992 ◽  
Vol 45 (12) ◽  
pp. 2089 ◽  
Author(s):  
EL Ghisalberti ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Structural Study ◽  
Spectroscopic Studies ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Chemical Evidence ◽  
Alder Adduct

The structure of the compound obtained on heating the naturally occurring clerodane furanoditerpene (1) had been formulated as (2) on the basis of spectroscopic studies. A single-crystal X-ray diffraction study on the dihydro derivative of (2) has confirmed this and provides support for the stereochemistry previously assigned to (1) on the basis of chemical evidence.

scholarly journals Design and synthesis of hybrid cyclophanes containing thiophene and indole units via Grignard reaction, Fischer indolization and ring-closing metathesis as key steps

2015 ◽  
Vol 11 ◽  
pp. 1514-1519 ◽  
Author(s):  
Sambasivarao Kotha ◽  
Ajay Kumar Chinnam ◽  
Mukesh Eknathrao Shirbhate
Keyword(s):  
Grignard Reaction ◽  
Ring Closing Metathesis ◽  
Design And Synthesis ◽  
Synthetic Strategy ◽  
Fischer Indolization ◽  
Grignard Addition ◽  
Key Steps

We demonstrate a new synthetic strategy to cyclophanes containing thiophene and indole moieties via Grignard addition, Fischer indolization and ring-closing metathesis as key steps.

scholarly journals A Covalent Organic Cage Compound Acting as a Supramolecular Shadow Mask for the Regioselective Functionalization of C60

2020 ◽  
Author(s):  
Viktoria Leonhardt ◽  
Stefanie Fimmel ◽  
Ana-Maria Krause ◽  
Florian Beuerle
Keyword(s):  
Mass Spectrometry ◽  
Single Crystal ◽  
High Selectivity ◽  
Shadow Mask ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Cage Compound ◽  
Vis Spectroscopy ◽  
Regioselective Functionalization

<div><div><div><p>A trigonal-bipyramidal covalent organic cage compound serves as an efficient host to form stable 1:1-complexes with C60 and C70. Fullerene encapsulation has been comprehensively studied by NMR and UV/Vis spectroscopy, mass spectrometry as well as single-crystal X-ray diffraction. Exohedral functionalization of encapsulated C60 via threefold Prato reaction revealed high selectivity for the symmetry-matched all-trans-3 addition pattern.</p></div></div></div>

Ring-Closing Metathesis Approach to Cage Propellanes Containing Oxepane and Tetrahydrofuran Hybrid System

Synthesis ◽  
2017 ◽  
Vol 49 (24) ◽  
pp. 5339-5350 ◽  
Author(s):  
Sambasivarao Kotha ◽  
Subba Cheekatla ◽  
Darshan Mhatre
Keyword(s):  
Claisen Rearrangement ◽  
Alder Reaction ◽  
Diels Alder ◽  
Ring Closing Metathesis ◽  
Cage Compounds ◽  
Transannular Cyclization ◽  
Diels Alder Reaction ◽  
Grignard Addition ◽  
Key Steps ◽  
First Time

The preparation of a variety of structurally interesting oxygenated cage compounds involving atom-economic processes such as Claisen rearrangement, Diels–Alder reaction, [2+2] photocycloaddition, and ring-closing metathesis (RCM) as key steps is reported. For the first time, oxepane ring system is introduced in cage framework using olefin metathesis as a key step. These cage systems assembled here are difficult to prepare by traditional methods. The synthetic sequence described here opens up new routes to higher order polycycles containing heteroatoms without the involvement of protecting groups. Transannular cyclization observed during Grignard addition and the RCM protocol used here may be applicable to generate unknown oxygenated cage systems.

scholarly journals Supramolecular Diversity of Oxabicyclo[2.2.2]octenes Formed between Substituted 2H-Pyran-2-ones and Vinyl-Moiety-Containing Dienophiles

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1714
Author(s):  
Krištof Kranjc ◽  
Amadej Juranovič ◽  
Marijan Kočevar ◽  
Franc Perdih
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Thermal Conditions ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
Secondary Product ◽  
X Ray ◽  
Primary Products ◽  
Stereogenic Centers ◽  
Pressure Synthesis

In Diels–Alder reactions, 2H-pyran-2-ones as dienes can yield a large variety of cycloadducts with up to four contiguous carbon stereogenic centers. Some of the potentially most useful, however difficult to prepare due to their low thermal stability, are the primary CO2-containing oxabicyclo[2.2.2]octenes, which could be formed as eight distinctive isomers (two sets of regioisomers, each of these composed of four different stereoisomers). A high-pressure synthesis of such products was recently described in a few cases where vinyl-moiety-containing dienophiles were used as synthetic equivalents of acetylene. However, structures of the primary products have been so far only rarely investigated in detail. Herein, we present seven novel single-crystal X-ray diffraction structures of such cycloadducts of both stereoisomeric forms, i.e., endo and exo. Additionally, we present a single-crystal structure of a rare case of a cyclohexadiene system stable at room temperature, obtained as a secondary product upon the retro-hetero-Diels–Alder elimination of CO2 under thermal conditions (microwave irradiation), during this elimination the symmetry is increased and out of eight initially possible isomers of the reactant, this number in the product is decreased to four. In oxabicyclo[2.2.2]octene compounds, centrosymmetric hydrogen bonding was found to be the predominant motif and diverse supramolecular patterns were observed due to rich variety of C–H⋯O and C–H⋯π interactions.

Diels-Alder additions of dimethyl acetylenedicarboxylate to sterically hindered cyclohexa-2,4-dienones. Formation and X-ray structure analysis of stereoisomeric bicyclo[2.2.2]octadienones

1983 ◽  
Vol 36 (7) ◽  
pp. 1361 ◽  
Author(s):  
H Becker ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Structure Analysis ◽  
Electronic Absorption ◽  
Spectral Properties ◽  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sterically Hindered

The Diels-Alder addition of dimethyl acetylenedicarboxylate to sterically hindered 2,4-cyclohexadienones (spiro-quinol ethers) gives rise to stereoisomeric bicyclo[2.2.2]octadienones. The structures of three of these have been elucidated by single-crystal X-ray diffraction methods and their 1H n.m.r. and electronic absorption spectral properties are reported.

Molecular Topology of Linked Anthracenes: X-Ray Structure Analyses of Alkyl Di-9-anthryl-glycolates, 9-Anthryl 9-Anthrylmethyl Ethers and Their Photoisomers

1989 ◽  
Vol 42 (11) ◽  
pp. 1869 ◽  
Author(s):  
HD Becker ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Alder Reaction ◽  
Diels Alder ◽  
Molecular Structures ◽  
Molecular Topology ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diels Alder Reaction ◽  
Photochemical Isomerization ◽  
Spatial Demand

The molecular structures of ethyl di-9-anthrylglycolate (1) and methyl di-9-anthrylglycolate (2), as well as those of three isomerization products of (2), have been established by single-crystal X-ray diffraction studies. In both (1) and (2), the anthracenemoieties are characterized by marked deviations from planarity. The stereospecific course of the thermal and photochemical isomerization of (2) by Diels -Alder reaction is suggested to be governed by the spatial demand of the alkoxycarbonyl group. Base-catalysed isomerization of (2) by migration of 9-anthryl from carbon to oxygen is associated with steric relief.

scholarly journals Design and synthesis of C 3-symmetric molecules bearing propellane moieties via cyclotrimerization and a ring-closing metathesis sequence

2018 ◽  
Vol 14 ◽  
pp. 2537-2544 ◽  
Author(s):  
Sambasivarao Kotha ◽  
Saidulu Todeti ◽  
Vikas R Aswar
Keyword(s):  
Benzene Ring ◽  
Alder Reaction ◽  
Diels Alder ◽  
Central Core ◽  
Ring Closing Metathesis ◽  
Design And Synthesis ◽  
Synthetic Strategy ◽  
Diels Alder Reaction ◽  
End Groups ◽  
Key Steps

We have developed an efficient synthetic strategy to assemble C 3-symmetric molecules containing propellane moieties as end groups and a benzene ring as a central core. The synthesis of these C 3-symmetric molecules involves simple starting materials. Our approach to C 3-symmetric compounds relies on a Diels–Alder reaction, cyclotrimerization and ring-closing metathesis as key steps.

scholarly journals One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

2020 ◽  
Vol 16 ◽  
pp. 1447-1455 ◽  
Author(s):  
Gui-Feng Kang ◽  
Gang Zhang
Keyword(s):  
Single Crystal ◽  
Dual Role ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
One Pot ◽  
Diverse Range ◽  
X Ray ◽  
One Pot Synthesis ◽  
Synthetic Strategy

A catalyst-free one-pot synthetic methodology was developed for the preparation of 1,3,5-triazine-2,4-dithione derivatives through three-component reactions of arylaldehydes, thiourea, and orthoformates. The procedure tolerated a diverse range of arylaldehydes and orthoformates and provided a rapid entry to a variety of 4-aryl-6-(alkylthio)-3,4-dihydro-1,3,5-triazine-2(1H)-thiones (29 examples). The synthetic strategy relies on the dual role of thiourea in the cyclization with the aldehydes and the alkylation via an intermediate imidate formation. The structures of 1,3,5-triazine-2,4-dithione derivatives were characterized by spectroscopic techniques as well as by single crystal X-ray diffraction.

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