The crystal structure and unambiguous absolute configuration of meleagrin (1) isolated from fungus Emericella dentata Nq45 is reported herein to first time on the bases of single crystal X-ray ...diffraction. Together with 1, haenamindole (2), isorugulosuvine (3), secalonic acid D (4), ergosterol (5) and cerebroside A (6) were obtained and their structures were determined by ESI MS and NMR data analysis. Diverse biological activity of meleagrin (1) was investigated. Compound 1 pronounced potent cytotoxicity against the human cervix carcinoma cell line KB-3-1 and its multidrug resistant sub-clone KB-V1 of IC
50
3.07 and 6.07 µM, respectively, in comparison with the reference (+) - griseofulvin (IC
50
19, 19.5 µM). Based on the antibiofilm activity, compound 1 displayed as well potent activity against Staphylococcus aureus with an MIC of 0.25 mg/mL. Isolation of the producing fungus and taxonomical characterization is stated as well.
The direct double carbenylation of 1,4-diiodobenzene and 4,4′-dibromobiphenyl with a classical N-heterocyclic carbene, SIPr (
1
) (SIPr = :C{
N
(2,6-iPr
2
C
6
H
3
)}
2
CH
2
CH
2
), by means of nickel ...catalysis gives rise to 1,3-imidazolinium salts (SIPr)(C
6
H
4
)(SIPr)(I)
2
(
2
) and (SIPr)(C
6
H
4
)
2
(SIPr)(Br)
2
(
3
) as off-white solids. Two-electron reduction of
2
and
3
with KC
8
cleanly yields Kekulé diradicaloid compounds (SIPr)(C
6
H
4
)(SIPr) (
4
) and (SIPr)(C
6
H
4
)
2
(SIPr) (
5
), respectively, as crystalline solids. Structural parameters and DFT as well as CASSCF calculations suggest the closed-shell singlet ground state for
4
and
5
. Calculations reveal a very low singlet-triplet energy gap Δ
E
S-T
for
5
(10.7 kcal mol
−1
), while Δ
E
S-T
for
4
(29.1 kcal mol
−1
) is rather large.
Two-electron reduction of bis(1,3-imidazolinium) salts
2
and
3
with KC
8
gives rise to stable diradicaloids
4
and
5
, respectively. Calculations reveal a very low singlet-triplet energy gap Δ
E
S-T
for
5
(10.7 kcal mol
−1
), while Δ
E
S-T
for
4
(29.1 kcal mol
−1
) is rather large.
Room temperature ionic liquids of cyclic sulfonimide anions
n
cPFSI
(ring size:
n
= 4-6) with the cations EMIm
+
(1-ethyl-3-methylimidazolium), BMIm
+
(1-butyl-3-methylimidazolium) and BMPL
+
(BMPL = ...1-butyl-1-methylpyrrolidinium) have been synthesized. Their solid-state structures have been elucidated by single-crystal X-ray diffraction and their physicochemical properties (thermal behaviour and stability, dynamic viscosity and specific conductivity) have been assessed. In addition, the ion diffusion was studied by pulsed field gradient stimulated echo (PFGSTE) NMR spectroscopy. The decisive influence of the ring size of the cyclic sulfonimide anions on the physicochemical properties of the ILs has been revealed. All ILs show different properties compared to those of the non-cyclic
TFSI
anion. While these differences are especially distinct for ILs with the very rigid
6cPFSI
anion, the 5-membered ring anion
5cPFSI
was found to result in ILs with relatively similar properties. The difference between the properties of the
TFSI
anion and the cyclic sulfonimide anions has been rationalized by the rigidity (conformational lock) of the cyclic sulfonimide anions. The comparison of selected IL properties was augmented by MD simulations. These highlight the importance of π
+
-π
+
interactions between pairs of EMIm
+
cations in the liquid phase. The π
+
-π
+
interactions are evident for the solid state from the molecular structures of the EMIm
+
-ILs with the three cyclic imide anions determined by single-crystal X-ray diffraction.
Ionic liquids with three cyclic perfluoroalkylsulfonylimide anions that are related to the bis(trifluoromethylsulfonyl)imide anion are described, which show the importance of conformational flexibility on IL properties.
Two-electron reduction of bis(1,3-imidazolinium) salts
2
and
3
with KC
8
gives rise to stable diradicaloids
4
and
5
, respectively. Calculations reveal a very low singlet–triplet energy gap Δ
E
S–T
...for
5
(10.7 kcal mol
–1
), while Δ
E
S–T
for
4
(29.1 kcal mol
–1
) is rather large.
The direct double carbenylation of 1,4-diiodobenzene and 4,4′-dibromobiphenyl with a classical N-heterocyclic carbene, SIPr (
1
) (SIPr = :C{
N
(2,6-iPr
2
C
6
H
3
)}
2
CH
2
CH
2
), by means of nickel catalysis gives rise to 1,3-imidazolinium salts (SIPr)(C
6
H
4
)(SIPr)(I)
2
(
2
) and (SIPr)(C
6
H
4
)
2
(SIPr)(Br)
2
(
3
) as off-white solids. Two-electron reduction of
2
and
3
with KC
8
cleanly yields Kekulé diradicaloid compounds (SIPr)(C
6
H
4
)(SIPr) (
4
) and (SIPr)(C
6
H
4
)
2
(SIPr) (
5
), respectively, as crystalline solids. Structural parameters and DFT as well as CASSCF calculations suggest the closed-shell singlet ground state for
4
and
5
. Calculations reveal a very low singlet–triplet energy gap Δ
E
S–T
for
5
(10.7 kcal mol
–1
), while Δ
E
S–T
for
4
(29.1 kcal mol
–1
) is rather large.
Mit Fluor zum Erfolg: Palladiumfluorokomplexe öffnen einen neuen Zugang zu Metallamakrocyclen. Die Vorstufe 1 reagiert mit den 1‐Trimethylsilyl‐Derivaten von Imidazol, 2‐Phenylimidazol oder Purin ...(siehe Schema) zu neutralen Molekülen wie der kelchförmigen Verbindung 2 (siehe Molekülstruktur, iPr‐Gruppen wurden weggelassen), die zu den seltenen neutralen Organometallmakrocyclen zählen und keine reduktive Eliminierung unter C‐N‐Verknüpfung eingehen.
The synthesis of the 1,1‘,3,3‘-tetrabutenyl-substituted metallocenes C5H3(CMe2CH2CHCH2)22M (M = Fe 1, Co 2, Ni 3), their electrochemical properties, and the solid-state structures of 1 and 3 are ...presented. Hydrosilylation of 1 with dimethylphenylsilane leads to C5H3(CMe2(CH2)3SiMe2Ph)22Fe, 4. The π-coordination ability of the arene system in 4 has allowed the preparation of the pentanuclear complex C5H3(CMe2(CH2)3SiMe2(η6-C6H5−Cr(CO)3)22Fe, 5, containing a ferrocene core and peripherial η6-coordinated Cr(CO)3 moieties. Electrochemical investigations of 5 show a reversible oxidation of the ferrocene unit as well as an independent, noninteracting irreversible oxidation of the Cr centers.
Chiral amino-functionalized silicon-bridged indene derivatives
4a
4c
were synthesized from 3-(2-(N,N-dialkylamino)ethyl)indenes
2a
2c
. The C-Si coupling reactions are regioselective, leading ...exclusively to the formation of 1,3-disubstituted isomers in a rac/meso ratio of 1:1, as indicated by NMR spectroscopy. The solid-state structure of the dimethylsilyl-bridged bisindene (R,R)-
4a
is described. The formation of corresponding ansa-zirconocenes via amine elimination chemistry was monitored by
1
H NMR spectroscopy.Key words: amino-functionalized indenes, silicon-bridged, ansa-metallocenes, chirality, regioselectivity, amine elimination chemistry.
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