21862-63-5Relevant articles and documents
Stereoselectivity in the Reduction of Cyclic Ketones with Sodium Borohydride. Effect of the Ratio of the Components of a Mixed Solvent of Tetrahydrofuran and Methanol
SOAI, Kenso,OHI, Kazumi
, p. 1601 - 1602 (1985)
Reduction of relatively conformationally rigid cyclic ketones with sodium borohydride was examined in a mixed solvent of tetrahydrofuran (THF)and methanol (MeOH) with varying the ratio of the components.The highest stereoselectivities of the reductions were observed in the mixed solvent, and not in each individual solvent.
A free radical method for reduction of cyclohexanones - Preferential formation of equatorial alcohols
Clive, Derrick L. J.,Cheng, Hua
, p. 1951 - 1961 (2003)
Cyclohexanones react with 2-hydroselenobenzoic acid to afford spiro-[4H-3,1-benzoxaselenin-2,1′-cyclohexan]-4-ones. Stannane reduction and basic hydrolysis gives epimeric cyclohexanols, with the equatorial isomer predominating.
Stereoselective Reduction of 4-tert-Butylcyclohexanone to cis-4-tert-Butylcyclohexanol catalysed by Zeolite BEA
Creyghton, Edward J.,Ganeshie, Soesiela D.,Downing, Roger S.,Bekkum, Herman van
, p. 1859 - 1860 (1995)
Zeolite BEA is found to be the first stereoselective and regenerable heterogeneous catalyst for the Meerwein-Ponndorf-Verley reduction of 4-tert-butylcyclohexanone to cis-4-tert-butylcyclohexanol.
Solvent Effects on the cis- and trans-4-t-Butylcyclohexanol Equilibrium by a New Method, using Gas-chromatographic Head-space Analysis
Abraham, Michael H.,Nasehzadeh, Asadollah,Cook, Michael J.,Kaberia, Festus
, p. 312 - 313 (1980)
Solvent effects on equilibria between configurational isomers of fixed conformation may be studied quantitatively by gas-chromatographic analysis of the head-space above solutions containing a standard ratio of the isomers; as an example, solvent effects on the cis- and trans-4-t-butylcyclohexanol equilibrium are reported.
Chemoselectivity of lithium aluminium hydride-(±)threo-1,16- dibenzyloxy,7,8-dihydroxy hexadecane-methanol complex in reduction of carbonyl compounds
Malkar,Kumar
, p. 977 - 993 (1998)
Modification of lithium aluminum hydride(LAH) with (±)-threo-1,16- dibenzyloxy,7,8-dihydroxy hexadecane, prepared from (±)-threo- 9,10,16- trihydroxy hexadecanoic acid(aleuritic acid) for chemo- and stereo-selective reduction of carbonyl compounds is reported. Aldehydes were selectively reduced in the presence of a highly reactive cyclohexanone and other ketones. Stereoselectivity in reduction of ketones was observed in cases where high levels of the reagent was used.
Tetrafluorosilane is a mild and very selective reagent for the cleavage of silyl-protected alcohols
Corey,Yi
, p. 2289 - 2290 (1992)
Silyl ethers are cleaved by SiF4 in CH2Cl2 or CH3CN at a rate which depends strongly on the steric screening of the ether oxygen, providing a promising method for selective desilylation under mild conditions.
Jones
, p. 2528,2531 (1960)
Synthesis and Reduction Ability of Borane Complexes of 2-Aminopyridine Derivative having a Chiral Center at the Amino Nitrogen
Yamaguchi, Yosbimi,Takada, Atsushi,Okamoto, Yosbihisa
, p. 1737 - 1739 (1997)
A novel method for synthesis of a chiral amine borane is described and selective reductions of carbonyl compounds with the amine borane are investigated.
The importance of entropy in stereoselection. Reduction of tert-butylcyclohexanone by lithium aluminum hydride
Rosenberg, Robert E.,Vilardo, Jonathan S.
, p. 2185 - 2188 (1996)
In the title reaction, the differences in both the enthalpy and the entropy of activation between the cis and trans diastereomers were measured (ΔΔH(≠) = -793 (56) cal/mol and ΔΔS(≠) = 2.00 (0.20) e.u.). The experimentally determined ΔΔH(≠) is shown to be
BIS(1,4-DIHYDRO-1-PYRIDYL)ZINC AND BIS(1,4-DIHYDRO-1-PYRIDYL)MAGNESIUM COMPLEXES; REDUCING PROPERTIES OF THE 1,4-DIHYDROPYRIDYL GROUP BOUND TO ZINC OR MAGNESIUM
Koning, A. J. De,Boersma, J.,Kerk, G. J. M. van der
, p. 173 - 184 (1980)
Bis(1,4-dihydro-1-pyridyl)zinc and -magnesium complexes are mild reducing agents.These compounds contain metal-bound 1,4-dihydropyridyl groups which act as hydride donors.In this paper we report the reactions of these new reagents with compounds which con
ACTIVATION OF REDUCING AGENTS. SODIUM HYDRIDE CONTAINING COMPLEX REDUCING AGENTS 28. STEREOCHEMISTRY OF REDUCTION OF KETONES BY COMPLEX REDUCING AGENTS
Feghouli, A.,Fort, Y.,Vanderesse, R.,Caubere, P.
, p. 1379 - 1382 (1988)
The stereochemistry of reduction of selected ketones by a variety of Complex Reducing Agents (MCRA) has been investigated.The selectivity depends on the nature of the CRA constituents and principally on that of the metal salt.
A fluorine-mediated boron reducing agent - sodium tris(pentafluorophenoxy)borohydride. Preparation and reaction with selected organic compounds containing representative functional groups. Facile diastereoselective reduction of substituted cyclohexanones
Fuller, Joseph C.,Karpinski, Matthew L.,Williamson, Stanley M.,Singaram, Bakthan
, p. 123 - 128 (1994)
Addition of 3 equiv. of pentafluorophenol to a tetrahydrofuran (THF) suspension of sodium borohydride at 0 deg C resulted in the rapid and quantitative formation of sodium tris(pentafluorophenoxy)borohydride (NaTPFPBH) with concurrent evolution of 3 equiv. of hydrogen gas.The reducing agent NaTPFPBH is stable at 0 deg C for an extended period of time without having to remain in equilibrium with an alkali metal hydride.The approximate rate and stoichiometry of the reaction of excess pure NaTPFPBH with 41 selected compounds containing representative functional groups was examined in order to characterize the reducing agent for selective reductions.Primary, secondary and tertiary alcohols evolved 1 equiv. of hydrogen slowly over a period of 24 h at 0 deg C.Phenol also liberated hydrogen slowly and the reaction of hexylamine was very slow.Aldehydes and reactive ketones are reduced readily and quantitatively to yield the corresponding alcohols.Carboxylic acids generated hydrogen quantitatively without undergoing any further reduction.Esters, lactones and phthalides are essentially inert towards the reagent.Epoxides are not reduced by NaTPFPBH.Primary aliphatic and aromatic amides evolved hydrogen but no significant reduction occurred.Unlike sodium and potassium borohydrides, NaTPFPBH is very stereo- and regio-selective. 2-Methylcyclohexanone is reduced predominantly to the corresponding less stable isomer, cis-2-methylcyclohexanol.Switching the order of addition of sodium borohydride and pentafluorophenol to reduce substituted cyclohexanones gave the thermodynamically more stable alcohols with an equatorial hydroxy group.Cinnamaldehyde and 2-cyclohexen-1-one are reduced readily to cinnamyl alcohol and 2-cyclohexen-1-ol, respectively.
Gas-phase hydrogenation of 4-tert-butylphenol over Pt/SiO2
Kalantar, Ahmad,Backman, Henrik,Carucci, Jose H.,Salmi, Tapio,Murzin, Dmitry Yu.
, p. 60 - 67 (2004)
Gas-phase hydrogenation of 4-tert-butylphenol (4-TBP) over 1% Pt/SiO 2 to cis and trans 4-tert-butylcyclohexanol (4-TBCHOL), via the intermediate 4-tert-butylcyclohexanone, was studied in a differential reactor at atmospheric pressure and at temperatures between 127 and 227°C. The formation of by-products due to hydrogenolysis played an important role in the reaction at temperatures over 200°C. The rates of 4-t-butylcyclohexanol and 4-t-butylcyclohexanone formation passed through a maximum at 187°C. The catalyst deactivation was also considerable. Being thermodynamically more stable the trans form of the alcohols isomers is produced in separate experiments by epimerization in the presence of hydrogen as an astoichiometric compound. The reaction network for the reaction is proposed.
SN2 Reaction of Diarylmethyl Anions at Secondary Alkyl and Cycloalkyl Carbons
Shinohara, Riku,Ogawa, Narihito,Kawashima, Hidehisa,Wada, Kyohei,Saito, Shun,Yamazaki, Takashi,Kobayashi, Yuichi
, p. 1461 - 1478 (2019/01/25)
The substitution reaction of the diethyl allylic and propargylic phosphates with Ar2CH anions was applied to sec-alkyl phosphates to compare reactivity and stereoselectivity. However, the substitution took place on the ethyl carbon of the diethyl phosphate group. We then found that the diphenyl phosphate leaving group ((PhO)2PO2) was suited for the substitution at the sec-alkyl carbon. Enantioenriched diphenyl sec-alkyl phosphates with different substituents (Me, Et, iPr) on the vicinal position underwent the substitution reaction with almost complete inversion (>99% enantiospecificity). The substitution reactions of cyclohexyl phosphates possessing cis or trans substituents (Me and/or tBu) at the C4, C3, and C2 positions of the cyclohexane ring were also studied to observe the difference in reactivity among the cis and trans isomers. A transition-state model with the phosphate leaving group ((PhO)2PO2) in the axial position was proposed to explain the difference. This model was supported by computational calculation of the virtual substitution reaction of the structurally simpler “dimethyl” cyclohexyl phosphates (leaving group = (MeO)2PO2) with MeLi. Furthermore, the calculation unexpectedly indicated higher propensity of (PhO)2PO2 as a leaving reactivity than alkyl phosphate groups such as (MeO)2PO2 and (iPrO)2PO2.
An efficient FeCl3-mediated approach for reduction of ketones through N-heterocyclic carbene boranes
Wang, Ming-Hui,Chen, Ling-Yan
supporting information, p. 732 - 735 (2017/03/31)
An efficient FeCl3-mediated approach for reduction of ketones by NHC-BH3 has been developed. A series of ketones were smoothly converted to the corresponding alcohols in good to excellent yields through NHC-BH3 reductive process.
