• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.546-550
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• 2014

Relative reactivity of various carbonyl and acid derivatives in MPV-type (Meerwein-Ponndorf-Verley) reduction with an DIBAL(F) model has been studied via DFT and MP2 methods. Free energies of initial adduct formation (-Gadd) of DIBAL(F) model and carbonyls are in the order of amide < ester < aldehyde < ketone < acid chloride; in the alan-amide adduct, the developed positive charge at carbonyl carbon is expected to be stabilized by amide resonance, but in the acid chloride adduct it is destabilized by inductive effect of chloride. However the TS barrier energies (${\Delta}G_{TS}$) for the MPV-type hydride reduction of the carbonyl adducts are in the order of aldehyde < ketone < acid chloride << ester < amide; presumably decreasing order of electrophilicity of carbonyl carbon at adducts, which is well correlated with experimental data. It is noted that the relative reactivity of carbonyl derivatives in MPV-type reduction with DIBAL(X) is not governed by the alan-adduct formation energies, but follows the order of electrophilicity of carbonyl carbon of transition states.

• Bulletin of the Korean Chemical Society
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• v.24 no.4
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• pp.453-459
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• 2003

(Pyridine)(tetrahydroborato)zinc complex, $[Zn(BH_4)_2(py)]$, as a stable white solid, was prepared quantitatively by complexation of an equimolar amount of zinc tetrahydroborate and pyridine at room temperature. This reagent can easily reduce variety of carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and a, β-unsaturated carbonyl compounds to their corresponding alcohols in good to excellent yields. Reduction reactions were performed in ether or THF at room temperature or under reflux conditions. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing agent.

• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.667-671
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• 2006

The new MPV-type reagents, B-acetoxydiisopinocampheylborane ($Ipc _2$BOAc) and B-trifluoroacetoxydiisopinocampheylborane $(Ipc _2BO _2CCF _3)$, have been prepared and their reducing characteristics in the reduction of carbonyl compound have been examined in order to find out a new reducing system with unique applicability in organic synthesis. In general, the reactivity of $Ipc _2BO _2CCF _3$ appears to be stronger than that of $Ipc _2$BOAc, presumably due to the acidity increase by the electron-withdrawing fluorine-substituent. Both reagents show an excellent selectivity in 1,2-reduction of $\alpha,\beta$-unsaturatedcarbonyl compounds and in competitive reduction between structurally different carbonyl compounds. In addition, $Ipc _2BO _2CCF _3$ shows interesting features in the stereoreduction of cyclic ketones.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2335-2339
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• 2013

Relative reactivity of various Al-substituted dialkylalans ($AlR_2(X)$) in reduction of acetone has been studied with density functional theory and MP2 method. Formation of the alan dimers and the alan-acetone adduct, and the transition state for the Meerwein-Ponndorf-Verley (MPV) type reduction of the adduct were calculated to figure out the energy profile. Formation of dimeric alans is highly exothermic. Both the relative free energies for acetone-alan adduct formation and the TS barriers for the MPV type reduction with respect to alan dimers and acetone were calculated and they show the same trend. Based on these energetic data, relative reactivity of alans is expected to be; $AlR_2(Cl)$ > $AlR_2(OTf)$ > $AlR_2(O_2CCF_3)$ > $AlR_2(F)$ > $AlR_2(OMs)$ > $AlR_2(OAc)$ > $AlR_2(OMe)$ > $AlR_2(NMe_2)$. The energy profile is relatively well correlated with the experimental order of the reactivity of Al-substituted dialkylalans. It is noted that the substituents of alans have initial effects on the relative free energies for the carbonyl-adduct formation. Therefore, an $AlR_2(X)$ which forms a more stable carbonyl-adduct is more reactive in carbonyl reduction.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2162-2190
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• 2007

The newly-developed Meerwein-Ponndorf-Verley (MVP) type reagents using aluminum, boron and other metals for reduction of organic functional groups such as carbonyl and epoxy compounds have been surveyed. highlighted and reviewed in this account are the appearance of new MPV type reagents and their application to the selective reduction of organic functions. Finally, this account emphasizes the distinct contrast in the reducing characteristics existed between metal hydride reagents and MPV reagents, and compares their usefulness in organic synthesis.

• Journal of the Korean Chemical Society
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• v.15 no.3
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• pp.117-120
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• 1971

Possibility of two phase reduction of carbonyl compounds to the corresponding alcohols was studied. Thus the 0.5 M ether solutions of the representative carbonyl compounds were treated with alkaline stabilized sodium borohydride aqueous solution at room temperature. Butyraldehyde was reduced rapidly within one hr., whereas other aldehydes tested; heptaldehyde, benzaldehyde, and 1-naphthaldehyde were reduced in 6-12 hr. 2-Heptanone was reduced much slowly; 87% in 48 hr., however, acetophenone was reduced moderately; 92% in 12 hr. and cycloalkanones were reduced rapidly (cyclohexanone in 0.5 hr., and cyclopentanone in 3-6 hr.).

• Journal of the Korean Chemical Society
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• v.18 no.5
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• pp.363-367
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• 1974

Approximate rate and stoichiometry of the reaction of ten compounds which contain functional group such as nitrile, nitro, halogen and one of these functional group together with a carbonyl group by the two phase reduction were tested at room temperature. Nitrile, nitro and halogen were all inert under these condition. Therefore selective reduction of carbonyl group in the presence of these group were examined. Thus m-nitrobenzaldehyde, m-nitroacetophenone, p-bromoacetophenone and p-cyanobenzaldehyde were reduced to corresponding alcohols in excellent yields, 95∼100 %.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2961-2966
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• 2010

Reduction of carbonyl compounds such as aldehydes, ketones, $\alpha,\beta$-unsaturated enals and enones, $\alpha$-diketones and acyloins was carried out readily with $NaBH_3CN$ in the presence of wet $SiO_2$ as a neutral media. The reactions were performed at solvent-free conditions in oil bath (70 - $80^{\circ}C$) or under microwave irradiation (240 W) to give the product alcohols in high to excellent yields. Regioselective 1,2-reduction of conjugated carbonyl compounds took place in a perfect selectivity without any side product formation.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1664-1670
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• 2003

$NaBH_4$ with catalytic amounts of $MoCl_5$ can readily reduce a variety of carbonyl compounds such as aldehydes, ketones, acyloins, ${\alpha}$-diketones and conjugated enones to their corresponding alcohols in good to excellent yields. Reduction reactions were performed under aprotic condition in $CH_3CN$ at room temperature or reflux. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing system.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.603-604
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• 2004