scholarly journals Pyrimidine-Substituted Hexaarylbenzenes as Versatile Building Blocks for N-doped Organic Materials

2021 ◽  
Author(s):  
Nicolas Meitinger ◽  
Alexander Klaus Mengele ◽  
Djawed Nauroozi ◽  
Sven Rau
Keyword(s):  
Building Blocks ◽  
Pyrimidine Ring ◽  
Diels Alder ◽  
Central Ring ◽  
Synthetic Procedure ◽  
Phenyl Rings ◽  
Solvent Molecules ◽  
Nano Graphene ◽  
Solid State Structures ◽  
Graphene Structures

Hexaarylbenzenes (HABs) are valuable precursors for the bottom-up synthesis of (nano-)graphene structures. In this work the synthesis of several bis-pyrimidine substituted HABs furnished with tert-butyl groups at different sites of the four pendant phenyl rings is reported. The synthetic procedure is based on modular [4+2]-Diels-Alder cycloaddition reactions followed by decarbonylation. Analysis of the solid-state structures revealed that the newly synthesized HABs feature a propeller-like arrangement of the six arylic substituents around the benzene core. Here, the tilt of the aryl rings with respect to the central ring is strongly depending on the intermolecular interactions between the HABs as well as co-crystallized solvent molecules. Interestingly, by evading the closest proximity of the central ring using an alkyne spacer, the distant pyrimidine ring is oriented in coplanar geometry with regard to the benzene core, giving rise to a completely different UV-absorption profile.

scholarly journals Furoic Acid and Derivatives as Atypical Dienes in Diels-Alder Reactions

2021 ◽  
Author(s):  
Razvan Cioc ◽  
Tom Smak ◽  
Marc Crockatt ◽  
Jan Kees Van der Waal ◽  
Pieter C A Bruijnincx
Keyword(s):  
Green Chemistry ◽  
Cycloaddition Reaction ◽  
Building Blocks ◽  
Diels Alder ◽  
Furoic Acid

The furan Diels-Alder (DA) cycloaddition reaction has become an important tool in green chemistry, being central to the sustainable synthesis of many chemical building blocks. The restriction to electron-rich furans...

scholarly journals Crystal structures and conformations of two Diels–Alder adduct derivatives: 1,8-bis(thiophen-2-yl)-14-oxatetracyclo[6.5.1.02,7.09,13]tetradeca-2(7),3,5-trien-10-one and 1,8-diphenyl-14-oxatetracyclo[6.5.1.02,7.09,13] tetradeca-2,4,6-trien-10-one

2015 ◽  
Vol 71 (2) ◽  
pp. 213-216
Author(s):  
S. Gopinath ◽  
P. Narayanan ◽  
K. Sethusankar ◽  
Meganathan Nandakumar ◽  
Arasambattu K. Mohanakrishnan
Keyword(s):  
Crystal Packing ◽  
Rotation Axis ◽  
Alder Reaction ◽  
Ring System ◽  
Diels Alder ◽  
Compound I ◽  
Diels Alder Reaction ◽  
Phenyl Rings ◽  
Axis Parallel ◽  
Alder Adduct

The title compounds, C21H16O2S2(I) and C25H20O2(II), are products of a tandem `pincer' Diels–Alder reaction consisting of [2 + 2] cycloadditions between benzo[c]furan and cyclopentanone. Each comprises a fused tetracyclic ring system containing two five-membered rings (inenvelopeconformations with the O atom as the flap) and six-membered rings (inboatconformations). In addition, two thiophene rings in (I) and two phenyl rings in (II) are attached to the tetracyclic ring system. The cyclopentanone ring adopts atwistedconformation in (I) and anenvelopeconformation in (II). In (I), the thiophene rings are positionally disordered over two sets of sites, with occupancy ratios of 0.901 (2):0.099 (2) and 0.666 (2):0.334 (2). In (II), the oxygen atom of the cyclopentanone ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4). The molecular structure of (I) is stabilized by an intramolecular C—H...O hydrogen bond, which generates anS(7) ring motif. In the crystal, the molecules are linkedviaweak C—H...O hydrogen bonds, which generateR22(16) ring motifs in (I) andC(8) chains in (II). In both structures, the crystal packing also features C—H...π interactions. The crystal studied of compound (I) was twinned by non-merohedry. The twin component is related by the twin law [−1 0 0 −0.101 1 −0.484 0 0 −1] operated by a twofold rotation axis parallel to thebaxis. The structure of (I) was refined with a twin scale factor of 0.275 (2).

scholarly journals Synthesis of fluorinated δ-lactams via cycloisomerization of gem-difluoropropargyl amides

2010 ◽  
Vol 6 ◽  
Author(s):  
Satoru Arimitsu ◽  
Gerald B Hammond
Keyword(s):  
Building Blocks ◽  
Alder Reaction ◽  
Diels Alder ◽  
Tandem Reaction ◽  
Enyne Metathesis ◽  
Metathesis Reaction ◽  
Ring Closing Metathesis ◽  
Diels Alder Reaction

gem-Difluoro-1,7-enyne amides are suitable building blocks for the synthesis of difluorodihydropyridinones via a ring-closing metathesis reaction, and of 4,4-difluoro-3-oxoisoquinolines through a ring-closing metathesis–enyne metathesis tandem reaction. These products, in turn, undergo a Diels–Alder reaction to yield heterotricyclic systems in moderate to good yields.

scholarly journals An aza-Diels–Alder route to quinoline-based unnatural amino acids and polypeptide surrogates

RSC Advances ◽  
2021 ◽  
Vol 11 (23) ◽  
pp. 14132-14139
Author(s):  
M. J. Umerani ◽  
H. Yang ◽  
P. Pratakshya ◽  
J. S. Nowick ◽  
A. A. Gorodetsky
Keyword(s):  
Amino Acids ◽  
Unnatural Amino Acids ◽  
Building Blocks ◽  
Solid Support ◽  
Diels Alder

The synthesis of quinoline-based unnatural amino acids and the subsequent preparation of polypeptide surrogates from these building blocks on solid support.

Cobalt(II) chloride adducts with acetonitrile, propan-2-ol and tetrahydrofuran: considerations on nuclearity, reactivity and synthetic applications

2017 ◽  
Vol 73 (2) ◽  
pp. 104-114 ◽  
Author(s):  
Danilo Stinghen ◽  
André Luis Rüdiger ◽  
Siddhartha O. K. Giese ◽  
Giovana G. Nunes ◽  
Jaísa F. Soares ◽  
...  
Keyword(s):  
Single Molecule ◽  
Building Blocks ◽  
Direct Reaction ◽  
X Ray Diffraction ◽  
Single Molecule Magnets ◽  
X Ray ◽  
Ft Ir ◽  
Bond Network ◽  
Solvent Molecules ◽  
Intramolecular Hydrogen

High-spin cobalt(II) complexes are considered useful building blocks for the synthesis of single-molecule magnets (SMM) because of their intrinsic magnetic anisotropy. In this work, three new cobalt(II) chloride adducts with labile ligands have been synthesized from anhydrous CoCl2, to be subsequently employed as starting materials for heterobimetallic compounds. The products were characterized by elemental, spectroscopic (EPR and FT–IR) and single-crystal X-ray diffraction analyses.trans-Tetrakis(acetonitrile-κN)bis(tetrahydrofuran-κO)cobalt(II) bis[(acetonitrile-κN)trichloridocobaltate(II)], [Co(C2H3N)4(C4H8O)2][CoCl3(C2H3N)]2, (1), comprises mononuclear ions and contains both acetonitrile and tetrahydrofuran (thf) ligands, The coordination polymercatena-poly[[tetrakis(propan-2-ol-κO)cobalt(II)]-μ-chlorido-[dichloridocobalt(II)]-μ-chlorido], [Co2Cl4(C3H8O)4], (2′), was prepared by direct reaction between anhydrous CoCl2and propan-2-ol in an attempt to rationalize the formation of the CoCl2–alcohol adduct (2), probably CoCl2(HOiPr)m. The binuclear complex di-μ-chlorido-1:2κ4Cl:Cl-dichlorido-2κ2Cl-tetrakis(tetrahydrofuran-1κO)dicobalt(II), [Co2Cl4(C4H8O)4], (3), was obtained from (2) after recrystallization from tetrahydrofuran. All three products present cobalt(II) centres in both octahedral and tetrahedral environments, the former usually less distorted than the latter, regardless of the nature of the neutral ligand. Product (2′) is stabilized by an intramolecular hydrogen-bond network that appears to favour atransarrangement of the chloride ligands in the octahedral moiety; this differs from thecisdisposition found in (3). The expected easy displacement of the bound solvent molecules from the metal coordination sphere makes the three compounds good candidates for suitable starting materials in a number of synthetic applications.

scholarly journals A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

2019 ◽  
Vol 15 ◽  
pp. 1523-1533 ◽  
Author(s):  
András György Németh ◽  
György Miklós Keserű ◽  
Péter Ábrányi-Balogh
Keyword(s):  
Elemental Sulfur ◽  
Building Blocks ◽  
Reaction Conditions ◽  
One Pot ◽  
Catalyst Free ◽  
Synthetic Procedure ◽  
Three Component Reaction ◽  
Wide Range ◽  
Organic Chemist ◽  
The One

A new multicomponent reaction has been developed between isocyanides, sulfur and alcohols or thiols under mild reaction conditions to afford O-thiocarbamates and dithiocarbamates in moderate to good yields. The one-pot reaction cascade involves the formation of an isothiocyanate intermediate, thus a catalyst-free synthesis of isothiocyanates, as valuable building blocks from isocyanides and sulfur is proposed, as well. The synthetic procedure suits the demand of a modern organic chemist, as it tolerates a wide range of functional groups, it is atom economic and easily scalable.

scholarly journals Endo and Exo Diels–Alder Adducts: Temperature-Tunable Building Blocks for Selective Chemical Functionalization

2018 ◽  
Vol 140 (15) ◽  
pp. 5009-5013 ◽  
Author(s):  
Emre H. Discekici ◽  
Andre H. St. Amant ◽  
Shay N. Nguyen ◽  
In-Hwan Lee ◽  
Craig J. Hawker ◽  
...  
Keyword(s):  
Building Blocks ◽  
Diels Alder ◽  
Chemical Functionalization ◽  
Selective Chemical
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