A general method for the preparation of silyl derivatives of platinum(II)

1967 ◽  
pp. 869 ◽  
Author(s):  
J. Chatt ◽  
C. Eaborn ◽  
S. Ibekwe ◽  
P. N. Kapoor
Keyword(s):  
Silyl Derivatives ◽  
Derivatives Of ◽  
General Method

Phase transfer catalytic synthesis of silyl derivatives of heterocyclic thiols

1999 ◽  
Vol 35 (9) ◽  
pp. 1052-1058 ◽  
Author(s):  
E. Abele ◽  
K. Rubina ◽  
R. Abele ◽  
I. Sleiksha ◽  
E. Lukevics
Keyword(s):  
Phase Transfer ◽  
Catalytic Synthesis ◽  
Silyl Derivatives ◽  
Derivatives Of

29Si-Kernresonanzuntersuchungen an N-Trimethylsilyl-substituierten Aminen und Amiden / 29Si Nuclear Magnetic Resonance Studies on N-Trimethylsilyl Derivatives of Amines and Amides

1977 ◽  
Vol 32 (2) ◽  
pp. 163-166 ◽  
Author(s):  
B. Heinz ◽  
H. C. Marsmann ◽  
U. Niemann
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Aromatic Amines ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electronic Charge ◽  
Magnetic Resonance Studies ◽  
Basic Character ◽  
Silyl Derivatives ◽  
Trimethylsilyl Derivatives ◽  
Derivatives Of

The 29Si chemical shifts of several trimethyl silyl derivatives of amines and amides are measured and compared to other chemical and theoretical properties such as the basicities or the electronic charge on the nitrogen or the hydrogen of the N-H group of the amine or the amide. Whereas the 29Si chemical shift of saturated amines can be rationalized in terms of substituent effects, the shifts of aromatic amines show some dependency on the basic character of the amine. There seems to be little correlation between 29Si chemical shifts and electronic charge, but there is a similarity of 29Si with 1H chemical shifts of the NH group, which is interpreted as depending on anisotropy effects.

scholarly journals Aconitum lipo-alkaloids – Semisynthetic Products of the Traditional Medicine

2011 ◽  
Vol 6 (4) ◽  
pp. 1934578X1100600 ◽  
Author(s):  
Botond Borcsa ◽  
Dezső Csupor ◽  
Peter Forgo ◽  
Ute Widowitz ◽  
Rudolf Bauer ◽  
...  
Keyword(s):  
Complex Mixture ◽  
Long Chain Fatty Acid ◽  
Diterpene Alkaloids ◽  
Highly Sensitive ◽  
Minor Compounds ◽  
The Individual ◽  
Traditional Processing ◽  
Far Eastern ◽  
Derivatives Of ◽  
General Method

The term lipo-alkaloid is used for C19 aconitane alkaloids containing one or two long-chain fatty acid residues. Lipo-alkaloids are transesterified derivatives of the most toxic and highly effective diester-type diterpene alkaloids, such as aconitine, hypaconitine, mesaconitine. Lipo-alkaloids are native minor compounds of aconite drugs, but their amount significantly increases after traditional processing, which is a general method in the Far Eastern traditional medicinal systems. Analytical works demonstrated that cautious processing (usually boiling) of crude aconite roots decreases the amount of normal diterpene alkaloids and increases the concentration of lipo-alkaloids resulting in the reduction of toxicity of the drugs. Many papers reported that lipo-alkaloids occur as a complex mixture in the drugs, and the isolation of the individual components is extremely difficult. These compounds have been identified using highly sensitive analytical methods (HPLC-MS, NMR), and semisynthetic approaches have been developed to ensure lipo-alkaloids in pure form for pharmacological studies. This review summarizes the structure, chemistry, semisynthesis, analytics and bioactivities of lipo-alkaloids. On the basis of 32 references this is the first comprehensive study on this topic, covering the data of 173 compounds.

Silyl Derivatives of the Mixed Sandwiches Cyclopentadienyl Manganese Benzene and Cyclopentadienyl Manganese Biphenyl, CpMn(C6H6) and CpMn(C6H5-Ph)

1997 ◽  
Vol 52 (9) ◽  
pp. 1037-1042 ◽  
Author(s):  
Max Herberhold ◽  
Thomas Hofmann ◽  
Stefanie Weinberger ◽  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
Membered Ring ◽  
Grignard Reagents ◽  
Sandwich Complexes ◽  
Subsequent Reaction ◽  
Silyl Derivatives ◽  
Magnesium Halide ◽  
Derivatives Of

Mixed manganese sandwich complexes containing a silyl-substituted cyclopentadienyl ring, e. g. (η5 - C5H4 - R)Mn(η6- C6H6) (3a - c) and (η5- C5H4 - R)Mn(η6- C6H5 - Ph) (4a - c); (R = SiMe3 (a), Si2Me5 (b) and SiMe2tBu (c)), were obtained in low yield via intermediates {(η5 - C5H4 - R)MnCl} and their reaction with phenyl Grignard reagents. Use of the 4-trimethylsilyl-phenyl magnesium halide in the reaction with the intermediate {CpMnCl} led to complexes with silylsubstituted arene rings, CpMn(η6 - C6H5 - R′) (5a) and CpMn(η6 -R′ - C6H5 - C6H5 - R′) (6a); (R′ = SiMe3 (a)). Dilithiation of CpMn6H6) (1) and subsequent reaction with a chlorosilane gave (η5-C5H4 - R)Mn(η6 - C6H5 - R′) (7a,b); (R = R′ = SiMe3 (a), Si2Me5 (b)). A cyclophane 8 in which five- and six-membered ring are linked through a -Me2Si-SiMe2- bridge was obtained using 1,2-dichloro-tetramethyldisilane. The mixed manganese sandw ich complexes were thoroughly characterized by 1H , 13C, 29Si and 55Mn NMR spectroscopy. The 55Mn spectra can be used to detect low-yield side-products.

Synthesis of Sterically Congested Carbamates of Carbohydrates through Organic Base Catalysis

Synthesis ◽  
2019 ◽  
Vol 51 (15) ◽  
pp. 2897-2908 ◽  
Author(s):  
Anji Chen ◽  
Dan Wang ◽  
Lalith P. Samankumara ◽  
Guijun Wang
Keyword(s):  
Hydroxy Group ◽  
Current Method ◽  
Building Blocks ◽  
Base Catalysis ◽  
Organic Base ◽  
Molecular Assemblies ◽  
Effective Catalyst ◽  
Organic Bases ◽  
Derivatives Of ◽  
General Method

4,6-O-Benzylidene acetal protected α-methoxy d-glucose and d-glucosamine are useful building blocks for the syntheses of carbohydrate derivatives and functional molecular assemblies. In this research, we have developed a general method for the preparation of C-3 carbamate derivatives of densely functionalized glucose and glucosamine with isocyanates using organic bases as catalysts. Without a suitable catalyst, the C-3 hydroxy group of the glucosamine derivative could not be converted into the corresponding carbamates when treated with isocyanates. Several organic bases were screened as the catalysts for the reactions, and we discovered that 5.0 mol% of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was an effective catalyst for the carbamoylation reaction. A library of both alkyl and aryl carbamate derivatives of the two sterically congested carbohydrates have been effectively synthesized using the current method.

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