Synthesis and conformational assignment of cis- and trans-2-amino-1-arylcyclohexanols

1985 ◽  
Vol 63 (11) ◽  
pp. 3186-3194 ◽  
Author(s):  
Antonio Delgado ◽  
Ricardo Granados ◽  
David Mauleon ◽  
Inmaculada Soucheiron ◽  
Miguel Feliz
Keyword(s):  
Aluminum Hydride ◽  
Chair Conformation ◽  
Lithium Aluminum ◽  
Aryl Group ◽  
Conformationally Restricted ◽  
H Nmr ◽  
Hydride Reduction ◽  
Reagent Treatment ◽  
Sodium Borohydride Reduction ◽  
Cis And Trans

The synthesis of cis- and trans-2-amino-1-arylcyclohexanols 1–8, conformationally restricted analogues of the α-adrenergic drugs norephedrine 9, methoxamine 10, and isopropylmethoxamine 11, is described. trans-Aminoalcohols were obtained through reaction of epoxides 12 or 13 with isopropylamine (to afford 4 and 8) or with sodium azide followed by lithium aluminum hydride reduction (to afford 2 and 6), whereas cis-aminoalcohols 1 and 5 were obtained by condensation of 2-aminocyclohexanone hydrobromide 26 with the appropriate organometallic reagent. Treatment of 1 and 5 with acetone followed by sodium borohydride reduction gave isopropylaminoalcohols 3 and 7. Configurational and conformational assignments of aminoalcohols 1–8 have been carried out on the basis of their 1H nmr and 13C nmr data and by comparison with reference diols 18 and 30. The major or exclusive chair conformation observed for all the compounds has an equatorial aryl group.

Synthesis oftrans- and cis-α-damascone

1978 ◽  
Vol 56 (10) ◽  
pp. 1368-1371 ◽  
Author(s):  
Hsing-Jang Liu ◽  
Hing-Kwok Hung ◽  
George L. Mhehe ◽  
M. L. Duarte Weinberg
Keyword(s):  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Complete Recovery ◽  
Lithium Aluminum ◽  
Magnesium Bromide ◽  
Keto Ester ◽  
Keto Esters ◽  
Hydride Reduction ◽  
Cis And Trans ◽  
Cis Isomer

Se lective thioketalization of a mixture of keto esters 5 and 6 resulted in the exclusive formation of thioketal 7 and complete recovery of keto ester 6. Lithium aluminum hydride reduction of thioketal 7 followed by Moffatt oxidation of the resulting alcohol 8 gave aldehyde 10 which on treatment with a mixture of cis- and trans-1-propenyl magnesium bromide afforded trans- alcohol 11 and its cis isomer 12. Manganese dioxide oxidation of alcohol 11 followed by desulfurization gave trans α-damascone (3). Similarly, alcohol 12 was converted to cis-α-damascone (4).

Berberidic acid

1979 ◽  
Vol 57 (13) ◽  
pp. 1647-1651 ◽  
Author(s):  
P. Chinnasamy ◽  
M. Shamma
Keyword(s):  
Lithium Aluminum Hydride ◽  
Mercuric Acetate ◽  
Dimethyl Ester ◽  
Pyridinium Salt ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
Acid Oxidation ◽  
Hydride Reduction ◽  
Sodium Borohydride Reduction ◽  
Nitric Acid Oxidation

Berberidic acid (2), obtained by nitric acid oxidation of berberine (1), can be esterified to diester 3, or to monoesters 4 and 5. Sodium borohydride reduction of 4 provides γ-lactone 6 which can be oxidized with iodine to pyridinium salt 7. In like fashion, monoester 5 leads to γ-lactone 8 which is oxidized by mercuric acetate to salt 9. Berberidic acid dimethyl ester (3) is hydrogenated to allo hexahydro diester 10 from which normal diester 11 can be derived by base isomerization. Hydrogenation of lactone 6 produces allo lactone 14 whose further reduction with lithium aluminum hydride gives diol 15. This same diol can also be obtained from the lithium aluminum hydride reduction of hexahydro diester 10. Alternatively, lithium aluminum hydride reduction of diester 11 gives rise to diol 16, diastereomeric with 15. Catalytic hydrogenation of lactone 8 provides normal lactone 18 which is transformed to diol 6 by lithium aluminum hydride.

The Chemistry of Sulfur Curing. III. Effects of Zinc Oxide on the Mechanism of the Reaction of Cyclohexene with Sulfur

1968 ◽  
Vol 41 (5) ◽  
pp. 1329-1338 ◽  
Author(s):  
James R. Wolfe ◽  
Thomas L. Pugh ◽  
A. Stanley Killian
Keyword(s):  
Zinc Oxide ◽  
Aluminum Hydride ◽  
Major Product ◽  
Lithium Aluminum ◽  
Chain Reaction ◽  
Radical Chain ◽  
Hydride Reduction ◽  
Cis And Trans ◽  
Radical Chain Reaction ◽  
Mechanism Of The Reaction

Abstract Reaction of cyclohexene and sulfur at 140° followed by lithium aluminum hydride reduction of the polysulfide products results in the formation of cyclohexanethiol, 2-cyclohexene-1-thiol, cis- and trans-1, 2-cyclohexanedithiol, and cyclohexyl sulfide. If zinc oxide is present during the reaction, trans-1, 2-cyclohexanedithiol is the major product. In the absence of zinc oxide, cis-1, 2-cyclohexanedithiol is the major product. It is postulated that in the absence of zinc oxide the reaction proceeds via a free radical chain involving polysulfenyl radicals accompanied by a secondary polar addition reaction of hydrosulfide products with cyclohexene. Zinc oxide when present is postulated to initiate an ionic chain reaction which, due to its greater velocity, dominates the radical chain reaction.

The Chemistry of Sulfur Curing. IV. Effects of Organic Accelerators on the Reaction of Cyclohexene with Sulfur

1968 ◽  
Vol 41 (5) ◽  
pp. 1339-1347 ◽  
Author(s):  
James R. Wolfe
Keyword(s):  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Major Product ◽  
Lithium Aluminum ◽  
Radical Mechanism ◽  
Secondary Products ◽  
Tetramethylthiuram Disulfide ◽  
Hydride Reduction ◽  
Free Radical Mechanism ◽  
Cis And Trans

Abstract Cyclohexene reacts with sulfur at 140° in the presence of zinc dimethyldithio-carbamate, tetramethylthiuram monosulfide, or tetramethylthiuram disulfide, to produce 2-cyclohexene-1-thiol as the major product after lithium aluminum hydride reduction of the polysulfide compounds. Secondary products are cis- and trans-1, 2-eyclohexanedithiol and cyclohexanethiol. Zinc dimethyldithiocarbamate is postulated to promote the reaction via an ionic mechanism as it causes more trans than cis-1, 2-cyclohexanedithiol to be formed. Tetramethylthiuram monosulfide and disulfide are postulated to promote the reaction via a free radical mechanism as they cause more cis- than trans-1, 2-cyclohexanedithiol to be formed.

Stereoselective synthesis of α-bulnesene, 4-epi-α-bulnesene, and 5-epi-α-bulnesene

1970 ◽  
Vol 48 (14) ◽  
pp. 2234-2245 ◽  
Author(s):  
Edward Piers ◽  
Kin Fai Cheng
Keyword(s):  
Sodium Borohydride ◽  
Lithium Aluminum Hydride ◽  
Stereoselective Synthesis ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
Borohydride Reduction ◽  
Similar Sequence ◽  
Hydride Reduction ◽  
Photochemical Rearrangement ◽  
Sodium Borohydride Reduction

Lithium–ammonia reduction of the hydroguaiazulene derivative 6, followed by oxidation of the resulting diol 13, gave, in a highly stereoselective manner, the keto alcohol 14. The latter was converted into 5-epi-α-bulnesene (2). In a similar sequence of reactions, 4-epi-α-bulnesene (3) was obtained from compound 9. Photochemical rearrangement of the previously obtained dienone 25 gave the hydroguaiazulene derivative 27. Successive subjection of the latter to acetylation, hydrogenation, and sodium borohydride reduction gave a mixture of the epimeric diols 31 and 32. When this mixture was treated with p-toluenesulfonic acid in pyridine, and the resulting olefinic diester 35 was sequentially subjected to hydrogenation [tris(triphenylphosphine)chlororhodium] and lithium aluminum hydride reduction, the crystalline diol 37 was obtained. The latter was converted into α-bulnesene (1) by standard reactions.

Free Radical Substitution Reactions of Sulfur Monochloride. A Limited Synthesis of Mercaptans

1973 ◽  
Vol 51 (20) ◽  
pp. 3366-3372 ◽  
Author(s):  
Dennis D. Tanner ◽  
Brian G. Brownlee
Keyword(s):  
Free Radical ◽  
Lithium Aluminum Hydride ◽  
Elemental Sulfur ◽  
Aluminum Hydride ◽  
Lithium Aluminum ◽  
Substitution Reactions ◽  
Sulfur Monochloride ◽  
Hydride Reduction ◽  
Abstraction Reaction ◽  
Radical Substitution

The photolysis of sulfur monochloride with a series of saturated aliphatic hydrocarbons yielded alkyl chlorides, di- and polysulfides, hydrogen chloride, and elemental sulfur. The free radical substitution reactions leading to the production of alkyl chloride and the di- and polysulfides were shown to proceed via a chlorine atom abstraction reaction. The major products, the di- and polysulfides could be transformed quantitatively, by lithium aluminum hydride reduction into their corresponding mercaptans. The reaction describes a simple free radical route to the synthesis of a variety of alkyl mercaptans.

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