17373-17-0Relevant academic research and scientific papers
Crystal Structural Study on 2:1 Complexes of Equatorial Isomers of 3,5-Dimethylcyclohexanone and 3,5-Dimethylcyclohexanol with 1,1,6,6-Tetraphenylhexa-2,4-diyne-1,6-diol
Toda, Fumio,Tanaka, Koichi,Kai, Akihiro,Tanaka, Naoki,Tsugiyama, Yuko,et al.
, p. 1375 - 1378 (1988)
Selective inclusion of the diequatorial isomer of 3,5-dimethylcyclohexanone and the triequatorial isomer of 3,5-dimethylcyclohexanol by 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol was observed.The crystal structure of these complexes was studied.
Cerium-free Luche reduction directed by rehydrated alumina
Jones-Mensah, Ebenezer,Nickerson, Leslie A.,Deobald, Jackson L.,Knox, Hailey J.,Ertel, Alyssa B.,Magolan, Jakob
, p. 3748 - 3753 (2016/06/06)
A 1,2-regioselective reduction of α,β-unsaturated ketones to their corresponding allylic alcohols is accomplished with NaBH4 in the presence of acidic activated alumina rehydrated to the Brockmann II grade by adding 3 % w/w water. The substrate scope includes eight ketones reduced in high regio- and diastereoselectivity to their corresponding allylic alcohols. This is the first example of the strategy of systematically tuning the surface chemistry of alumina via partial rehydration in order to modulate selectivity in a reaction. Alumina is an appealing alternative to the common Luche reduction additive, CeCl3, from the perspective of cost and procedural simplicity.
Highly chemoselective catalytic hydrogenation of unsaturated ketones and aldehydes to unsaturated alcohols using phosphine-stabilized copper(I) hydride complexes
Chen, Jian-Xin,Daeuble, John F.,Brestensky, Donna M.,Stryker, Jeffrey M.
, p. 2153 - 2166 (2007/10/03)
A base metal hydrogenation catalyst composed of the phenyldimethylphosphine-stabilized copper(I) hydride complex provides for the highly chemoselective hydrogenation of unsaturated ketones and aldehydes to unsaturated alcohols, including the regioselective 1,2-reduction of α,β- unsaturated ketones and aldehydes to allylic alcohols. The active catalyst can be derived in situ by phosphine exchange using commercial [(Ph3P)CuH]6 or from the reaction of copper(l) chloride, sodium tert-butoxide, and dimethylphenylphosphine under hydrogen. The catalyst derived from 1,1,1- tris(diphenylphosphinomethyl)ethane is mechanistically interesting but less synthetically useful. (C) 2000 Elsevier Science Ltd.
Transfer Hydrogenation of Ketones with (1-) as the Precatalyst
Bhaduri, Sumit,Sharma, Krishna,Mukesh, Doble
, p. 1191 - 1200 (2007/10/02)
The cluster 1a has been found to be an efficient precatalyst for the transfer hydrogenations of ketones and α,β-unsaturated ketones.With substrates such as (5S)-carvone , (3R)-methylcyclopentanone and (3R)-methylcyclohexanone, moderate to high diastereoselectivities were observed for reduction of the conjugated olefinic and ketonic functionalities respectively.Aromatisation of carvone to 5-isopropyl-2-methylphenol and disproportionation of cyclohex-2-en-1-one to phenol and cyclohexanone have also been found to be catalysed by 1a.Studies with radical inhibitors and other evidence suggest a radical mechanism for the transfer-hydrogenation and aromatisation reactions.In the transfer hydrogenation of cyclohex-2-en-1-one, the rate of conversion of 1a into other soluble species can be modelled accurately if autocatalysis is assumed.The time-dependent concentration profiles of cyclohex-2-en-1-one, cyclohexanone and cyclohexanol are simulated well if autocatalytic formation of an active intermediate followed by consecutive reactions leading to the formation of products is assumed.Such a model is also consistent with the proposed radical mechanism.
Hydride-Mediated Homogeneous Catalysis. Catalytic Reduction of α,β-Unsaturated Ketones Using 6 and H2
Mahoney, Wayne S.,Stryker, Jeffrey M.
, p. 8818 - 8823 (2007/10/02)
Hydride-mediated reduction of α,β-unsaturated ketones catalytic in the hydride reagent is reported using 6 and molecular hydrogen.The reaction proceeds at room temperature and is highly regioselective, affording either the product of conjugate reduction or complete 1,4- and 1,2-reduction to the saturated alcohol, depending on reaction conditions.In the presence of excess phosphine, the process is homogeneous and chemoselective: isolated double bonds are not hydrogenated, even under forcing conditions.This novel catalytic reduction appears to proceed viathe heterolytic activation of molecular hydrogen by highly reactive copper(I) enolate and alkoxide intermediates.
The Predominance and Quantification of Steric Effects in the Solvolysis of Secondary Aliphatic Esters
Schneider, Hans-Joerg,Becker, Norman,Schmidt, Guenther,Thomas, Fred
, p. 3602 - 3607 (2007/10/02)
The solvolysis rates of 35 tosylates in hexafluoroisopropyl alcohol are measured and compared to MM2 calculated strain energies, ΔSI, between weighted sp3 states and the lowest sp2 state.For unhindered (pseudo)equatorially substituted cycloalkyl tosylates a linear correlation, free from ambiguities involved, e.g., with the leaving group simulation, is obtained which shows a sensitivity of m=1.04+/-0.05, indicating an extremely late transition state or limiting behavior.Based on the corresponding equation, it is shown that alkyl substituents in the γ- and in the β-position do not promote significant rate increases, even when there is an antiperiplanar disposition between the leaving group and a migrating β-methyl substituent.Instead, these substituents can lead to substantial ΔG* increase (by up to 5 kcal/mol in comparison to the ΔSI prediction), which is related to steric hindrance of solvation and/or hindrance for elimination. 17-(Tosyloxy)androstanes show extremely large epimeric rate ratios of>30000; these are not due to anchimeric assistance but only to the exceedingly slow reaction of the hindered 17β isomer, whereas the fast reaction of the 17α tosylate (e.g. 200 times higher than cyclopentyl tosylate) is in line with the ΔSI calculation. endo-Bicycloheptane esters show evidence for steric hindrance; exo-norbornyl tosylate has, however, a ΔG* value lower by 4 kcal/mol than predicted. ks/kc values, obtained by rate comparison in 80percent ethanol and 97percent HFIP, vary between 0.5 and 300, mainly as a result of different steric hindrance to rearside nucleophilic subnstitution
