REACTION MECHANISM STUDIES: 2. REDUCTIVE ELIMINATION OF 1,2-DIHALIDES WITH LITHIUM ALUMINUM HYDRIDE

1964 ◽  
Vol 42 (6) ◽  
pp. 1294-1314 ◽  
Author(s):  
J. F. King ◽  
R. G. Pews
Keyword(s):  
Reaction Mechanism ◽  
Lithium Aluminum Hydride ◽  
General Scheme ◽  
Aluminum Hydride ◽  
Reductive Elimination ◽  
Lithium Aluminum ◽  
Elimination Reaction ◽  
Complex Hydrides ◽  
Steric Factors ◽  
Related Compounds

1,2-Dibromides and bromohydrin p-toluenesulphonates of favorable geometry are readily reduced by lithium aluminum hydride in good yield to the corresponding olefin. Small quantities of water are found to have a temporaryacceleratingeffect on the reduction. The normal course of the reaction is a trans elimination, but when steric factors inhibit this, then substitution or cis elimination reactions may occur. It is shown that the cis elimination in the case of cis-1,2-dibromocyclohexane cannot involve reduction to the monobromide followed by dehydrobromination to the olefin. The reaction of some other 1,2-dihalides and related compounds with lithium aluminum hydride, and the reaction of a 1,2-dibromide with a number of other complex hydrides are reported.A general scheme for the mechanism of the olefin-forming elimination reaction is proposed. The limits that this study places on the possible positions of the reductive elimination of 1,2-dibromides with lithium aluminum hydride within this general scheme are discussed.

TETRAHYDROFURANS: I. 2,2-DIMETHYL-4-SUBSTITUTED-4-HYDROXYMETHYLTETRAHYDROFURANS AND RELATED COMPOUNDS

1961 ◽  
Vol 39 (4) ◽  
pp. 923-932 ◽  
Author(s):  
B. K. Wasson ◽  
C. H. Gleason ◽  
I. Levi ◽  
J. M. Parker ◽  
L. M. Thompson ◽  
...  
Keyword(s):  
Acetic Anhydride ◽  
Pharmacological Activity ◽  
Lithium Aluminum Hydride ◽  
Catalytic Reduction ◽  
Aluminum Hydride ◽  
Mineral Acid ◽  
Lithium Aluminum ◽  
Pyridine Hydrochloride ◽  
Cyclic Compounds ◽  
Related Compounds

Substituted methallylmalonic esters (I) were reduced with lithium aluminum hydride to the corresponding 2-methallyl-1,3-propanediols (II). These diols II underwent cyclization on treatment with a mineral acid to the isomeric 2,2-dimethyl-4-substituted-4-hydroxymethyltetrahydrofurans (IV). II and IV were converted to the respective carbamates III and V, which exhibited pharmacological activity. The assigned structures of the cyclic compounds IV were proved by infrared analyses and the following transformations. Ring scission of 2,2-dimethyl-4-allyl-4-hydroxymethyltetrahydrofuran (IVe) with acetic anhydride – pyridine hydrochloride yielded 2-allyl-2-methallyl-1,3-propanediol diacetate (Xe). Catalytic reduction of IVe gave 2,2-dimethyl-4-n-propyl-4-hydroxymethyltetrahydrofuran (IVd). Reductive cleavage of the tosylate VIIIb of 2,2,4-trimethyl-4-hydroxymethyltetrahydrofuran (IVb) with lithium aluminum hydride yielded the known 2,2,4,4-tetramethyltetrahydrofuran (IXb).

Derivatives of 2-pyrazolin-5-one. V. Preparation and properties of 1′,2′-dihydrospiro[[2]pyrazoline-4,3′ (4′H)-quinoline]-5-one.derivatives and related compounds

1977 ◽  
Vol 55 (15) ◽  
pp. 2856-2866 ◽  
Author(s):  
Ronald T. Coutts ◽  
Abdel-Monaem El-Hawari
Keyword(s):  
Acetic Acid ◽  
Sodium Borohydride ◽  
Lithium Aluminum Hydride ◽  
Catalytic Reduction ◽  
Aluminum Hydride ◽  
Spiro Compounds ◽  
Lithium Aluminum ◽  
Aldehydes And Ketones ◽  
Derivatives Of ◽  
Related Compounds

1′,2′-Dihydro-3-methyl-1-phenylspiro[[2]pyrazoline-4,3′(4′H)-quinoline]-5-one (8q), the structurally related 1,3-diphenylspiro[pyrazolone-quinoline] 8r and numerous 2′-substituted derivatives of 8q and 8r are readily accessible from catalytic reduction of 3-methyl-1-phenyl- or 1,3-diphenyl-4-(2-nitrobenzyl)-2-pyrazolin-5-one (1a, 1b, respectively) in alcohols (with the incorporation of the alkylidene moiety) or by interaction of the corresponding 2-aminobenzyl precursors (3a, 3b) with appropriate aldehydes and ketones. All spiro compounds were characterized by mass, ir, and 1Hmr spectra. The products obtained by reducing the spiro compounds with sodium borohydride and with lithium aluminum hydride are described. Reduction of 1a and 1b with zinc and acetic acid gave 3-methyl-1-phenyl- and 1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline (2a, 2b, respectively).

Synthesis of Some Epiminocyclohexanes by Hydride Reduction of α,β-Unsaturated Cyclohexanone Oximes and the Pyrolytic cis-Elimination of N-Acetylepiminocyclohexanes

1973 ◽  
Vol 51 (3) ◽  
pp. 427-432 ◽  
Author(s):  
J. R. Dimmock ◽  
W. A. Turner ◽  
P. J. Smith ◽  
R. G. Sutherland
Keyword(s):  
Mass Spectrum ◽  
Reaction Mechanism ◽  
Acetic Anhydride ◽  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
Fragmentation Pathways ◽  
Hydride Reduction

Reduction of several 2-benzylidenecyclohexanone oximes with lithium aluminum hydride gave the corresponding 1-benzyl-1,2-epiminocyclohexanes. Reduction of 2-benzylidenecyclohexanone oxime with lithium aluminum deuteride gave an epiminocyclohexane (8) which had incorporated two deuterium atoms. A reaction mechanism for the reduction is postulated. The major fragmentation pathways in the mass spectrum of 8 are outlined. Acetylation of 1-benzyl-1,2-epiminocyclohexane with acetic anhydride (15 min reflux) gave 3-acetamido-2-benzyl-1-cyclohexene by a pyrolytic cis elimination.

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