• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.97-101
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• 1991

Gas-phase pyrolyses of carbonate esters, ${\alpha}$- and ${\beta}$-hydroxy esters and ${\beta}$-hydroxy ketones have been studied theoretically by the AM1 MO method. Carbonate esters were found to decompose by two types of processes; in the reaction pathway involving an intermediate, the decomposition of the intermediate was rate-limiting, but direct pyrolyses were also possible via a six-membered cyclic transition state in which the methoxy oxygen attacks a hydrogen atom on the ${\beta}$-carbon. The hydroxy esters and ketones were found to decompose in a concerted process involving a six-membered cyclic transition state. Successive methylation on the ${\alpha}$- and ${\gamma}$-carbon led to an increase in the reactivity in agreement with experiments.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.211-214
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• 1987

Asymmetric reduction of a series of aliphatic ketones and representative other classes of ketones with potassium 9-O-isopinocampheyloxy-9-boratabicyclo[3.3.1]non ane (K 9-O-Ipc-9-BBNH) was studied. All the ketones examined were reduced smoothly to the corresponding alcohols in THF at -$78^{\circ}C$. Thus, the reduction of 2-butanone, 3-methyl-2-butanone, 3,3-dimethyl-2-butanone, 2-octanone, and 4-phenyl-2-butanone provides 51% ee, 61% ee, 44% ee, 35% ee, and 33% ee of optical inductions, respectively. The reduction of other classes of ketones gave 52% ee for 2,2-dimethylcyclopentanone, 47% ee for acetophenone, 23% ee for 3-acetylpyridine, 50% ee for methyl benzoylformate, 4.8% ee for 2-chloroacetophenone, 30% ee for trans-4-phenyl-3-butene-2-one, and 2% ee for 4-phenyl-3-butyn-2-one. Thus, the reagent was found to be most useful in the asymmetric reduction of acyclic and cyclic aliphatic series of ketones.

• Bulletin of the Korean Chemical Society
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• v.21 no.1
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• pp.128-130
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• 2000

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.689-690
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• 1997

• Bulletin of the Korean Chemical Society
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• v.21 no.6
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• pp.659-661
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• 2000

• Journal of the Korean Chemical Society
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• v.40 no.11
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• pp.699-701
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• 1996

• Bulletin of the Korean Chemical Society
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• v.17 no.10
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• pp.900-905
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• 1996

Details are described of reaction of carbonyl compounds with diisobutyldialkylaminoalane (DIBAL-NR2; R=Et, i-Bu, Ph) in order to establish their reduction characteristics. The reagents were extremely mild and reduced only aldehydes and ketones effectively in ethyl ether at 25 ℃. The stereoselectivity in the reduction of representative cyclic ketones appeared not so high but quite different from that obtained by DIBAL-H itself. The reagents reduced α,β-unsaturated aldehydes and ketones to the corresponding allylic alcohols without any detectable 1,4-reduction products. DIBAL-NR2 also achieved the selective reduction of aldehydes or ketones in the presence of keto or other readily reducible functional group, however the chemoselectivity was less satisfactory than that achieved by diisobutylethoxyalane (DI-BAL-OEt).

• Bulletin of the Korean Chemical Society
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• v.19 no.2
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• pp.236-242
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• 1998

Reaction of carbonyl compounds with Al-alkoxydiisobutylalane (DIBAOR, R=H, Et, i-Pr, t-Bu) has been investigated in detail so as to establish their usefulness as selective reducing agents in organic synthesis. The reagents appear to be extremely mild and can reduce only aldehydes and ketones effectively under mild conditions. All the other common organic functional groups are not affected by these reagents. The reagents can also reduce α,β-unsaturated aldehydes and ketones to the corresponding allylic alcohols without any detectable 1,4-reduction. Furthermore, the reagents show a highly chemoselective discrimination between aldehyde and ketone, between aldehydes, and between ketones. Even more remarkable is the stereoselective reduction of cyclic ketones to the thermodynamically more stable alcohol epimers.

• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.66-69
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• 1986

The reaction of potassium trialkoxyborohydrides of varying steric requirements with lithium chloride in tetrahydrofuran(THF) was examined in detail to establish the generality of this synthesis of the corresponding lithium trialkoxyborohydrides. The metal ion exchange reaction between potassium triisopropoxyborohydride and lithium chloride in THF proceeded instantly at room temperature and the corresponding lithium salt was very stable toward disproportionation. However, for R = s-Bu, t-Bu and 2-methylcyclohexyl, with increasing steric requirement, the lithium derivatives were unstable and thus dissociated into $(RO)BH_3^-\;and\; (RO)_4B^-$. The stereoselectivity of lithium triisopropoxyborohydride(LIPBH) in the reduction of representative cyclic ketones was examined and compared with that of the potassium derivative.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.840-844
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• 2010

The new MPV type reagent, Al-methanesulfonyldiisobutylalane ($DIBAO_3SCH_3$), has been prepared and its reducing characteristics in the reduction of selected organic compounds containing representative functional groups have been examined in order to find out a new reducing system with high selectivity in organic synthesis. In general, the reagent is extremely mild, showing only reactivity toward aldehydes, ketones and epoxides. The reagent exhibits a unique reducing applicability in organic synthesis. Thus, the reagent can achieve a clean 1,2-reduction of $\alpha,\beta$-unsaturated aldehydes and ketones to produce the corresponding allylic alcohols in 100% purity. In addition, the reagent shows an excellent regioselectivity in the ring-opening reaction of epoxides. Finally, $DIBAO_3SCH_3$ shows a high stereoselectivity in the reduction of cyclic ketones to produce the thermodynamically more stable epimers exclusively.