Flavan derivatives. XIII. The formation of 1,3-Diarylpropan-2-ols and 2,3-Diarylpropan-1-ols from Flavan-3-ols

1965 ◽  
Vol 18 (3) ◽  
pp. 389 ◽  
Author(s):  
JW Clark-Lewis ◽  
GC Ramsay
Keyword(s):  
Molecular Complex ◽  
Liquid Ammonia ◽  
Reduction Method ◽  
Optical Purity ◽  
Specific Rotation ◽  
Aluminium Chloride ◽  
Lithium Aluminium Hydride ◽  
Mechanism Of Formation ◽  
Lithium Aluminium ◽  
Trimethyl Ether

No change in specific rotation of (-)-1-(3,4-dimethoxyphenyl)-3-(2,4,6- trimethoxyphenyl)propan-2-ol was observed during attempted resolution, so that the propanol is probably close to optical purity in spite of its low specific rotation. (-)-Epigallocatechin pentamethyl ether was reduced with sodium and liquid ammonia to an analogous hexamethoxydiarylpropan-2-ol. Several conditions for reducing ( +)-catechin tetramethyl ether with lithium aluminium hydride-aluminium chloride mixtures were examined, and the reduction method was applied to (-)- epiafzelechin trimethyl ether and to (-)-epigallocatechin pentamethyl ether. The mechanism of formation of the (-)-2,3-diarylpropan-1-ol from (+)-catechin and (-)-epicatechin tetramethyl ethers is discussed. The 5,7,4'-trimethyl ethers of (-)-epiafzelechin and (�)-dihydrokaempferol were found to form a 1 : 1 molecular complex.

Preparation of secondary alcohols of high optical purity

1986 ◽  
Vol 51 (2) ◽  
pp. 401-403 ◽  
Author(s):  
Otakar Červinka ◽  
Anna Fábryová ◽  
Irina Sablukova
Keyword(s):  
Nmr Spectroscopy ◽  
Optical Purity ◽  
Optically Active ◽  
Secondary Alcohols ◽  
Lithium Aluminium Hydride ◽  
Enantioselective Reduction ◽  
H Nmr ◽  
Lithium Aluminium ◽  
High Optical Purity ◽  
Optically Pure

Partially resolved enantiomers of optically active alcohols I-V, obtained by enantioselective reduction of the corresponding ketones with lithium aluminium hydride in the presence of (-)-quinine, were converted into crystalline 3,5-dinitrobenzoates or phenylcarbamates. The esters of the nearly optically pure enantiomers were separated by crystallization from the generally more soluble esters of the racemates. Optical purity of the hydrolytically liberated alcohols was determined by 1H NMR spectroscopy in the presence of chiral shifting agents.

HYDROGENOLYSIS BY LITHIUM ALUMINIUM HYDRIDE – ALUMINIUM CHLORIDE OF ETHER SOLUTIONS OF CAMPHOR ETHYLENE KETAL AND NORCAMPHOR ETHYLENE KETAL

1966 ◽  
Vol 44 (13) ◽  
pp. 1547-1550 ◽  
Author(s):  
W. W. Zajac Jr. ◽  
B. Rhee ◽  
R. K. Brown
Keyword(s):  
Reductive Cleavage ◽  
Aluminium Chloride ◽  
Lithium Aluminium Hydride ◽  
Similar Reduction ◽  
Lithium Aluminium

The lithium aluminium hydride – aluminium chloride reductive cleavage of norcamphor ethylene ketal yields 2-(2-endo-norbornyloxy)ethanol in ≥98% yield, whereas the similar reduction of camphor ethylene ketal gives 2-(2-isobornyloxy)ethanol in 78% yield and 2-(2-bornyloxy)ethanol in 22% yield. These are the products arising from steric approach control.

Lithium aluminium hydride-aluminium chloride reduction of steroidal cyclic acetals

1971 ◽  
Vol 24 (1) ◽  
pp. 143 ◽  
Author(s):  
MS Ahmad ◽  
SC Logani
Keyword(s):  
Spectral Properties ◽  
Aluminium Chloride ◽  
Chemical Transformations ◽  
Lithium Aluminium Hydride ◽  
Glycol Ethers ◽  
Cyclic Acetals ◽  
Lithium Aluminium

Lithium aluminium hydride-aluminium chloride (1 : 1, AlH2Cl) reduction of 3,3-ethylenedioxycholest-5-ene (5), 3,3-ethylenedioxy-5α-oholestane (7), 6,6-ethyl-enedioxy-5α-cholestane (7), and 3,3-(1?- methylethylenedioxy)cholest-5-en (8a), gave the glycol ethers (9), (17), (21a), and (24), respectively. The structures of the ethers (9), (17), (21a), and (24) have been established by their spectral properties and chemical transformations. A mechanism of the hydrogenolysis is presented.

Flavan derivatives. XXVI. 3(3')-Hydroxyisochromano(4',3':2,3)chromans. Mechanism of formation of these hemiketals from 1'-Oxo-isochromono-(4',3':2,3)chromones

1969 ◽  
Vol 22 (11) ◽  
pp. 2389 ◽  
Author(s):  
JW Clark-Lewis ◽  
EW Della ◽  
MM Mahandru
Keyword(s):  
Carboxylic Acids ◽  
Carbonyl Group ◽  
Lactone Ring ◽  
Direct Reduction ◽  
Hydroxyl Group ◽  
Lithium Aluminium Hydride ◽  
Mechanism Of Formation ◽  
Hydride Ion ◽  
Lithium Aluminium ◽  
Nucleophilic Displacement

Reduction of the lactones of flavonol-2?-carboxylic acids [1?- oxoisochromono-(4?,3?:2,3)chromones] to hemiacetals by lithium aluminium hydride is shown to proceed by fission of the lactone ring accompanied by direct reduction of the chromone carbonyl group without fission of the chromone ring. The intermediate chrom-2-en-4-ols undergo nucleophilic displacement of the allylic (and benzylic) hydroxyl group by hydride ion attack at the 2- and 4-positions. Reduction of 7- methoxyisochromeno(4?,3?:2,3)chromone with lithium aluminium deuteride led to 7-methoxyisochromeno(4?,3?:2,3)chromen with 95% incorporation of two deuterium atoms.

Regulators of cell division in plant tissues. VII. The synthesis of zeatin and related 6-substituted purines

1969 ◽  
Vol 22 (1) ◽  
pp. 205 ◽  
Author(s):  
DS Letham ◽  
RE Mitchell ◽  
T Cebalo ◽  
DW Stanton
Keyword(s):  
Zea Mays ◽  
Cell Division ◽  
Acid Hydrolysis ◽  
Sodium Borohydride ◽  
Aluminium Chloride ◽  
Plant Tissues ◽  
Lithium Aluminium Hydride ◽  
Lithium Aluminium

6-(4-Hydroxy-3-methylbut-trans-2-enylamino)purine (zeatin), a cytokinin isolated from Zea mays, has been synthesized by a new route. β- Methylcrotononitrile was brominated with N-bromosuccinimide yielding γ- bromo-β-methylcrotononitrile, from which trans-γ-acetoxy-β- methylcrotononitrile was prepared. The alcohol derived from this acetate was converted into trans-β-methyl-γ-(tetrahydropyran-2- yloxy)crotononitrile. Reduction and acid hydrolysis gave 4-amino-2- methylbut-trans-2-en-1-ol which was made to react with 6-chloropurine to yield zeatin. ��� Several γ-alkoxy-β-methylcrotononitriles were prepared and reduced by aluminium chloride-lithium aluminium hydride to the corresponding unsaturated amines. Saturated nitrile formation also occurred in these reductions. The amines prepared were condensed with 6-chloropurine to yield a series of O-alkylzeatins. A number of other zeatin analogues were also synthesized. Two 6-methoxyalkylamino-purines were cleaved by sodium borohydride in the presence of iodine to 6-hydroxy- alkylaminopurines.

scholarly journals Reduction of Chalcones by Complex Metal Hydrides. III. Chalcone and Chain-deuterated Chalcones with Lithium Aluminium Hydride-Aluminium Chloride.

1969 ◽  
Vol 23 ◽  
pp. 2409-2413 ◽  
Author(s):  
Tapio Hase ◽  
Boris Holm ◽  
Johannes Thomsen ◽  
Károly Kovács ◽  
Alf A. Lindberg ◽  
...  
Keyword(s):  
Metal Hydrides ◽  
Aluminium Chloride ◽  
Lithium Aluminium Hydride ◽  
Complex Metal ◽  
Lithium Aluminium
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