Reduction of Organic Compounds by Lithium in Low Molecular Weight Amines. I. Selective Reduction of Aromatic Hydrocarbons to Monoölefins

Benkeser, Robert A.; Robinson, Robert E.; Sauve, Dale M.; Thomas, Owen H.

doi:10.1021/ja01617a025

Cited by 92 publications

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“…The foremost synthetic tool for selective dihydro‐addition is the Birch reduction. It proceeds via single electron and proton transfer steps involving a radical anion transition state; alkali metals dissolved in ammonia serve as electron and an alcohol as the proton donor . Under Birch conditions, 1 is reduced to the non‐conjugated 1,4,5,8‐tetrahydronaphthalene ( 3 ) (Scheme b) .…”

Section: Methodsmentioning

confidence: 99%

“…It proceeds via single electrona nd proton transfer steps involving ar adical anion transition state;a lkali metals dissolved in ammonias erve as electron and an alcohol as the protond onor. [2][3][4] UnderB irch conditions, 1 is reduced to the non-conjugated 1,4,5,8-tetrahydronaphthalene (3)( Scheme 1b). [5] The direct reduction to a conjugated product is not feasible by Birch reduction as such products are susceptible to further reduction.…”

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confidence: 99%

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Enantioselective Enzymatic Naphthoyl Ring Reduction

Willistein

Haas

Fuchs

et al. 2018

Chemistry A European J

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Birch reductions of aromatic hydrocarbons by means of single-electron-transfer steps depend on alkali metals, ammonia, and cryogenic reaction conditions. In contrast, 2-naphthoyl-coenzyme A (2-NCoA) and 5,6-dihydro-2-NCoA (5,6-DHNCoA) reductases catalyze two two-electron reductions of the naphthoyl-ring system to tetrahydronaphthoyl-CoA at ambient temperature. Using a number of substrate analogues, we provide evidence for a Meisenheimer complex-analogous intermediate during 2-NCoA reduction, whereas the subsequent reduction of 5,6-dihydro-2-NCoA is suggested to proceed via an unprecedented cationic transition state. Using vibrational circular dichroism (VCD) spectroscopy, we demonstrate that both enzymatic reductions are highly stereoselective in D O, providing an enantioselective pathway to products inaccessible by Birch reduction. Moreover, we demonstrate the power of VCD spectroscopy to determine the absolute configuration of isotopically engendered alicyclic stereocenters.

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Section: Methodsmentioning

confidence: 99%

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Enantioselective Enzymatic Naphthoyl Ring Reduction

Willistein

Haas

Fuchs

et al. 2018

Chemistry A European J

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“…[11] The Birch reduction of aromatic substrates such as benzene, naphthalene, and anthracene has been studied extensively. [2] A modification of this dissolving-metal reduction was developed by Benkeser, [12] who obtained more highly reduced products relative to the classic Birch reduction by replacing the ammonia solvent with a low-molecular-weight amine such as ethylenediamine, ethylamine, tert-butylamine, or diethylamine.…”

Section: Introductionmentioning

confidence: 99%

Formation, Isolation, and Spectroscopic Properties of Some Isomers of C₆₀H₃₈, C₆₀H₄₀, C₆₀H₄₂, and C₆₀H₄₄ − Analysis of the Effect of the Different Shapes of Various Helium‐Containing Hydrogenated Fullerenes on Their ³He Chemical Shifts

et al. 2003

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A complex mixture of C60H38 to C60H44 has been prepared by a much milder procedure (Benkeser reduction) than the hydrogenation procedures that have frequently been used to produce such highly hydrogenated derivatives of C60. 1H and 13C NMR spectra of fractions isolated by HPLC showed that more highly hydrogenated fullerenes exhibited signals that were shifted upfield. The opposite trend appears to hold in 3He NMR spectra of the corresponding endohedral helium compounds. The changes in the 1H, 13C, and 3He chemical shifts are reasonable for fullerenes hydrogenated to different extents. In particular, previously reported substantial changes in the shapes of the various hydrogenated fullerenes can reasonably account for the interesting trends apparent both in the 3He chemical shifts of He@C60Hx (x = 0−44) and in the HPLC retention times of the corresponding non‐helium‐containing species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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“…Reductions employing sodium or lithium in ethylamine can yield different results than when they are employed in liquid ammonia (15,16). Hallsworth and Henbest (16) found that the course of reductive ring opening of 5P,6P-epoxycholestane could be altered when ethylamine was used with Can.…”

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“…The mixture could be simplified considerably by oxidation with pyridinium chlorochromate (PCC) to afford only three compounds, none, however, being the desired cyclosteroid. The compounds identified were the C-5 epimeric 4,4-dimethylcholestane-3,6-diones (15,16) and 4,4-dimethylcholest-5-en-3-one (10). The 5 a dione 15 was the major product (50%).…”

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The chemistry of 5β,6β-epoxy-4,4-dimethylcholest-1-en-3-one. Approaches to the synthesis of 1α,5α-cyclosteroids. Part II

Georghiou¹,

Ren²

1993

Can. J. Chem.

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. Can. J. Chem. 71, 364 (1993).Epoxidation of 4,4-dimethylcholesta-1,5-dien-3-one (9) with MCPBA gives a mixture of the corresponding epimeric 5a,6a and 5P,6P epoxides. The major product is the 5P,6P epimer 6, in contradiction to what has been reported by others. The unambiguous assignment of the structures of these epoxides is based upon NMR NOED experiments. The chemistry of the 5P,6P epoxide is described in the context of unsuccessful attempts at synthesizing the corresponding l a , 5 a cyclosteroids. Reductive methods using lithium -liquid ammonia, lithium-ethylamine, or tri-n-butyl-or triphenyltin-AIBN gave products in which the a,P-unsaturated carbonyl system and the epoxide were reduced. When 6 was treated with BF,.etherate a B-nor derivative 27 was formed, presumably via a pinacol-type rearrangement.PARIS E. GEORGHIOU et YI REN. Can. J. Chem. 71, 364 (1993). L'Cpoxydation de la 4,4-dimCthylcholesta-1,5-dikn-3-one (9) par 1'AMCPB conduit 5 un melange des Cpoxydes Cpimeres correspondants 5a,6a et 5P,6P. Contrairement a ce qui a Ct C rapport6 par d'autres, le produit majeur est 1'Cpimkre 5P,6P (6). L'attribution non-ambigue des structures de ces Cpoxydes est basCe sur des experiences de RMN <. On dCcrit la chimie de 1'Cpoxyde 5P,6P dans le contexte d'essais infructueux de synthkse des la,5a cyclostCroides correspondants. Les reductions 5 l'aide de lithium -ammoniac liquide, de lithium-kthylamine ou des tri-n-butyl-ou triphCnylCtain-AIBN conduisent a des produits dans lesquels le systkme carbonyle a,p-insaturC et l'kpoxyde sont rCduits. Le traitement du produit 6 par du BF,.ether conduit a la formaton du derive B-nor 27, probablement par un rkarrangement de type pinacolique.[Traduit par la rCdaction]Introduction ~yclocholestan-7-one (3) via lithium -liquid ammonia The la,5a cyclocholesterols are relatively rare. Laing and reduction of cholest-5-ene-l,7-dione. More recently we Sykes (1, 2) reported the synthesis of la,5a-~yclochol~~t-2-~u~~e e d e d in synthesizing 4,4-dimethyl-la,5a-cyclochoene (I), and ~~-a c e t o x y -~~,~~-c y c~o c~o~e s t a n -6~o n e

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Reduction of Organic Compounds by Lithium in Low Molecular Weight Amines. I. Selective Reduction of Aromatic Hydrocarbons to Monoölefins

Cited by 92 publications

References 0 publications

Enantioselective Enzymatic Naphthoyl Ring Reduction

Enantioselective Enzymatic Naphthoyl Ring Reduction

Formation, Isolation, and Spectroscopic Properties of Some Isomers of C₆₀H₃₈, C₆₀H₄₀, C₆₀H₄₂, and C₆₀H₄₄ − Analysis of the Effect of the Different Shapes of Various Helium‐Containing Hydrogenated Fullerenes on Their ³He Chemical Shifts

The chemistry of 5β,6β-epoxy-4,4-dimethylcholest-1-en-3-one. Approaches to the synthesis of 1α,5α-cyclosteroids. Part II

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Reduction of Organic Compounds by Lithium in Low Molecular Weight Amines. I. Selective Reduction of Aromatic Hydrocarbons to Monoölefins

Cited by 92 publications

References 0 publications

Enantioselective Enzymatic Naphthoyl Ring Reduction

Enantioselective Enzymatic Naphthoyl Ring Reduction

Formation, Isolation, and Spectroscopic Properties of Some Isomers of C60H38, C60H40, C60H42, and C60H44 − Analysis of the Effect of the Different Shapes of Various Helium‐Containing Hydrogenated Fullerenes on Their 3He Chemical Shifts

The chemistry of 5β,6β-epoxy-4,4-dimethylcholest-1-en-3-one. Approaches to the synthesis of 1α,5α-cyclosteroids. Part II

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Formation, Isolation, and Spectroscopic Properties of Some Isomers of C₆₀H₃₈, C₆₀H₄₀, C₆₀H₄₂, and C₆₀H₄₄ − Analysis of the Effect of the Different Shapes of Various Helium‐Containing Hydrogenated Fullerenes on Their ³He Chemical Shifts