16 research outputs found
Synthesis of 2‑Aminoquinazolinones via Carbonylative Coupling of <i>ortho</i>-Iodoanilines and Cyanamide
Herein, we describe a convenient
and efficient synthesis of 2-aminoquinazolin-4Â(3<i>H</i>)-ones and N1-substituted 2-aminoquinazolin-4Â(1<i>H</i>)-ones by a domino carbonylation/cyclization process. The
reaction proceeds via carbonylative coupling of readily available <i>ortho</i>-iodoanilines with cyanamide followed by in situ ring
closure of an <i>N</i>-cyanobenzamide intermediate. The
products were easily isolated by precipitation in moderate to excellent
yields for a wide range of substrates, making this a highly attractive
method for the synthesis of 2-aminoquinazolinones
Synthesis of 2‑Aminoquinazolinones via Carbonylative Coupling of <i>ortho</i>-Iodoanilines and Cyanamide
Herein, we describe a convenient
and efficient synthesis of 2-aminoquinazolin-4Â(3<i>H</i>)-ones and N1-substituted 2-aminoquinazolin-4Â(1<i>H</i>)-ones by a domino carbonylation/cyclization process. The
reaction proceeds via carbonylative coupling of readily available <i>ortho</i>-iodoanilines with cyanamide followed by in situ ring
closure of an <i>N</i>-cyanobenzamide intermediate. The
products were easily isolated by precipitation in moderate to excellent
yields for a wide range of substrates, making this a highly attractive
method for the synthesis of 2-aminoquinazolinones
Synthesis of N‑Sulfonyl Amidines and Acyl Sulfonyl Ureas from Sulfonyl Azides, Carbon Monoxide, and Amides
A Pd-catalyzed
and ligand-free carbonylation/cycloaddition/decarboxylation cascade
synthesis of sulfonyl amidines from sulfonyl azides and substituted
amides at low CO pressure is reported. The reaction proceeds via an
initial Pd-catalyzed carbonylative generation of sulfonyl isocyanates
from sulfonyl azides, followed by a [2 + 2] cycloaddition with amides
and subsequent decarboxylation, which liberates the desired sulfonyl
amidines, generating N<sub>2</sub> and CO<sub>2</sub> as the only
reaction byproducts. Using this simple protocol, a diverse range of
sulfonyl amidines was obtained in moderate to excellent yields. In
addition, the reaction can also be directed through a more conventional
amidocarbonylation pathway by employing N-monosubstituted amide nucleophiles
to afford acyl sulfonyl ureas in good yields
Aminocarbonylations Employing Mo(CO)<sub>6</sub> and a Bridged Two-Vial System: Allowing the Use of Nitro Group Substituted Aryl Iodides and Aryl Bromides
A bridged two-vial system aminocarbonylation protocol
where MoÂ(CO)<sub>6</sub> functions as an external <i>in situ</i> solid source
of CO has been developed. For the first time both nitro group containing
aryl/heteroaryl iodides and bromides gave good to excellent yields
in the MoÂ(CO)<sub>6</sub>-mediated and palladium(0)-catalyzed conversion
to benzamides, while the identical one-vessel protocol afforded extensive
reduction of the nitro functionality. The above-mentioned bridged
two-compartment protocol furnished good results with both primary
amines and secondary amines and sluggish aniline nucleophiles at 65–85
°C reaction temperatures
Palladium(0)-Catalyzed Carbonylative One-Pot Synthesis of N‑Acylguanidines
A convenient synthetic strategy toward <i>N</i>-acylguanidines
via a sequential one-pot multicomponent carbonylation/amination reaction
has been developed. The compounds were readily obtained via an <i>N</i>-cyanobenzamide intermediate formed from the Pd(0)-catalyzed
carbonylative coupling of cyanamide and aryl iodides or bromides.
Subsequent amination with a large variety of amines provided the final <i>N</i>-acylguanidines, with the overall formation of one C–C
and two C–N bonds, in moderate to excellent yields. The substrate
scope was found to be wide and the methodology was used to produce
over 50 compounds, including 29 novel molecules. Furthermore, three
separate nitrogen-containing heterocycles were prepared from the <i>N</i>-acylguanidines synthesized using the developed multicomponent,
carbonylative method
Synthesis of Sulfonyl Azides via Diazotransfer using an Imidazole-1-sulfonyl Azide Salt: Scope and <sup>15</sup>N NMR Labeling Experiments
Imidazole-1-sulfonyl azide hydrogen
sulfate is presented as an
efficient reagent for the synthesis of sulfonyl azides from primary
sulfonamides. The described method is experimentally simple and high-yielding
and does not require the addition of Cu salts. Furthermore, <sup>15</sup>N NMR mechanistic studies show the reaction proceeds via a diazo
transfer mechanism. Imidazole-1-sulfonyl azide hydrogen sulfate provides
a considerable advantage over existing diazo transfer reagents in
terms of impact stability, cost, and ease of use
Microwave-Assisted Branching Cascades: A Route to Diverse 3,4-Dihydroquinazolinone-Embedded Polyheterocyclic Scaffolds
A novel metal-free
microwave-assisted branching cascades strategy
for the efficient synthesis of 3,4-dihydroÂquinazolinone-embedded
polyheterocyclic scaffolds is reported. Starting from in situ generated
key <i>N</i>-acyliminium ion precursors, 12 distinct and
skeletally diverse polycyclic frameworks were accessed in a single
step/pot via adjustment of the nucleophile(s) and reaction conditions.
Postcascade functionalization of these compounds was also demonstrated,
proving the utility of this method in accessing structurally diverse
chemical entities
Synthesis of 4‑Quinolones via a Carbonylative Sonogashira Cross-Coupling Using Molybdenum Hexacarbonyl as a CO Source
A palladium-catalyzed
CO gas-free carbonylative Sonogashira/cyclization
sequence for the preparation of functionalized 4-quinolones from 2-iodoanilines
and alkynes via two different protocols is described. The first method
(A) yields the cyclized products after only 20 min of microwave (MW)
heating at 120 °C. The second method (B) is a gas-free one-pot
two-step sequence which runs at room temperature, allowing the use
of sensitive substituents (e.g., nitro and bromide groups). For both
protocols, molybdenum hexacarbonyl was used as a solid source of CO
Direct Palladium(II)-Catalyzed Synthesis of Arylamidines from Aryltrifluoroborates
A fast and convenient synthesis of arylamidines starting from readily available potassium aryltrifluoroborates and cyanamides is reported. The coupling was achieved by Pd(II)-catalysis in a one step 20 min microwave protocol using Pd(O<sub>2</sub>CCF<sub>3</sub>), 6-methyl-2,2′-bipyridyl, TFA, and MeOH, providing the corresponding arylamidines in moderate to excellent yields
Route to 3‑Amidino Indoles via Pd(II)-Catalyzed C–H Bond Activation
We report a facile synthesis of 3-amidino
indoles from indoles
and cyanamides. The reaction is PdÂ(II)-catalyzed and proceeds via
C–H bond activation of the indole in its 3-position followed
by a 1,2-addition of the resulting indole–palladium σ-complex
to a cyanamide, which provides the corresponding amidine. The preference
for 4,5-diazafluoren-9-one (DAF) as the ligand is investigated using
DFT calculations, and a plausible reaction pathway is presented