GELSEMINE: III. REDUCTION WITH LITHIUM ALUMINUM HYDRIDE

1951 ◽  
Vol 29 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Morris Kates ◽  
Léo Marion
Keyword(s):  
Absorption Spectrum ◽  
Infrared Absorption ◽  
Lithium Aluminum Hydride ◽  
Infrared Absorption Spectrum ◽  
Secondary Alcohol ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
Basic Nitrogen ◽  
Group Reduction ◽  
Methylene Group

The infrared absorption spectrum of gelsemine indicates the presence of a carbonyl group. Reduction of the alkaloid with lithium aluminum hydride converts the carbonyl not to a secondary alcohol, but to a methylene group, thus indicating that the carbonyl is present in a lactamic grouping. The reduced base shows the properties of a substituted aniline. Since gelsemine has been shown to yield 3-ethylindole on dehydrogenation with selenium and since the N-atom involved in the lactamic group cannot be the strongly basic nitrogen, gelsemine must contain an oxindole grouping. Furthermore, 3-monosubstituted oxindoles are converted by lithium aluminum hydride to 3-substituted indoles, whereas gelsemine under the same conditions gives rise to a dihydroindole. Therefore, the alkaloid must contain a 3, 3-disubstituted oxindole grouping.

THE REACTION OF DIETHYL AZODICARBOXYLATE WITH DIHYDROGELSEMINE

1955 ◽  
Vol 33 (4) ◽  
pp. 604-609 ◽  
Author(s):  
Thelma Habgood ◽  
Léo Marion
Keyword(s):  
Infrared Spectrum ◽  
Methyl Ether ◽  
Sodium Borohydride ◽  
Lithium Aluminum Hydride ◽  
Chromic Acid ◽  
Aluminum Hydride ◽  
Membered Ring ◽  
Lithium Aluminum ◽  
Diethyl Azodicarboxylate ◽  
Methylene Group

Dihydrogelsemine reacts with diethyl azodicarboxylate yielding a carbinolamine which forms a methyl ether. Both this ether and the carbinolamine base can be oxidized by chromic acid to the same neutral lactam. That there has been no rearrangement of the carbon skeleton during these reactions is shown by reduction of the methyl ether of the carbinolamine with sodium borohydride to dihydrogelsemine and by reduction of the lactam with lithium aluminum hydride to tetrahydrodesoxygelsemine. It is concluded that both dihydrogelsemine and gelsemine contain a methylene group adjacent to N(b), and from the infrared spectrum of the lactam of dihydrogelsemine, N(b) appears to be part of a five-membered ring.

A synthetic route to 4-C-methyl-xylo-furanose

1979 ◽  
Vol 57 (21) ◽  
pp. 2818-2822 ◽  
Author(s):  
Tim Fat Tam ◽  
Bert Fraser-Reid
Keyword(s):  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
Synthetic Route ◽  
Indirect Methods ◽  
Hydroxymethyl Group ◽  
Major Isomer ◽  
Group Reduction ◽  
Cannizzaro Reaction

3-O-benzyl-1,2-isopropylidene-α-D-xylo-pentodialdofuranose could not be α-methylated by direct or indirect methods. The aldol product from reaction of the dialdofuranose with formaldehyde could not be trapped, but underwent a Cannizzaro reaction to give the C-4-bis-hydroxymethyl product. The latter can be regioselectively sulfonated at the pro-(S) hydroxymethyl group. Reduction with lithium aluminum hydride then affords 3-O-benzyl-1,2-isopropylidene-4-C-methyl-α-D-xylo-furanose as the major isomer, the configuration of which is proved by transformation into an oxetane.

PITHECOLOBINE, THE ALKALOID OF PITHECOLOBIUMSAMAN BENTH. I

1952 ◽  
Vol 30 (10) ◽  
pp. 761-772 ◽  
Author(s):  
K. Wiesner ◽  
D. M. MacDonald ◽  
Z. Valenta ◽  
R. Armstrong
Keyword(s):  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Ultraviolet Spectrum ◽  
Hydroxyl Group ◽  
Lithium Aluminum ◽  
Amino Groups ◽  
Saturated Compound ◽  
Secondary Amino ◽  
Trimethyl Amine ◽  
Methylene Group

Pithecolobine, C22H46N4O2, has a lactam group, one primary and two secondary amino groups, and a hydroxyl group. Lithium aluminum hydride converts it into a monocyclic saturated compound, desoxypithecolobine, C22H48N4. Hofmann degradation of this compound gives tetramethylputrescine, trimethyl amine, a doubly unsaturated base C16H31N with a terminal methylene group, and a base C16H34N2. Heating with selenium yields a hydrocarbon, C12;H24–26, with a sequence of six or more CH2 groups. A crystalline oxygen-free compound with two nitrogens (m.p.94 °C.) is also obtained, the ultraviolet spectrum of which is almost identical with aminopyridine.

Synthesis of Novel Chiral Pyrimidone Salts and their Application in Asymmetric Diethylzinc Addition of Arylaldehydes

2018 ◽  
Vol 15 (1) ◽  
pp. 137-142 ◽  
Author(s):  
Bi-Hui Zhou ◽  
Wei-Ping He ◽  
Lin-Lin Li ◽  
Li-Mei Fan ◽  
Xiang-Rong Li ◽  
...  
Keyword(s):  
Thionyl Chloride ◽  
Lithium Aluminum Hydride ◽  
Secondary Alcohol ◽  
Aluminum Hydride ◽  
Heterocyclic Carbenes ◽  
Ammonium Salts ◽  
Lithium Aluminum ◽  
Partial Reduction ◽  
Subsequent Reaction ◽  
Efficient Route

Aims and Objectives: When compared to five-membered N-heterocyclic carbene, recent reports have demonstrated that ring expanded NHCs showed rather different properties such as increased basicity (nucleophilicity) and greater steric demand. These unique features provide an opportunity to design new chiral ligands. This study was undertaken to design and synthesize a series of novel enantiopure pyrimidone salts, the precursors of N-heterocyclic carbenes, and their activity in asymmetric diethylzinc addition of arylaldehydes was demonstrated as well. Materials and Method: Commercially available dimethylmalonic acid was treated with thionyl chloride to form dimethylmalony dichloride, followed by subsequent reaction with different chiral primary amine produced corresponding diamide. Next, conversion of diamide to monoamide was achieved by partial reduction with lithium aluminum hydride. Finally, cyclization of monoamide with triethyl orthoformate in the presence of ammonium salts provided pyrimidone salts in good yields. Results: Seven enantiopure pyrimidone salts, the precursors of N-heterocyclic carbenes, have been synthesized starting from dimethylmalonic acid. Their applicability in asymmetric diethylzinc addition of arylaldehydes has been demonstrated and the corresponding secondary alcohol was obtained with good yields and moderate enantioselectivities. Conclusion: Herein we developed an efficient route to prepare a series of novel N-heterocyclic carbene precursors, which were demonstrated as effective catalysts for asymmetric diethylzinc addition of arylaldehydes, and the corresponding secondary alcohol was obtained with good yields and moderate enantioselectivities.

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