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Biomedical subjects

Miwako Mori

Publications and source records attributed to Miwako Mori.

28 records · Page 2Linked to original sources
PubMed2002

Asymmetric cyclization of omega-formyl-1,3-dienes catalyzed by a zerovalent nickel complex in the presence of silanes.

A nickel(0)-catalyzed asymmetric cyclization of omega-formyl-1,3-diene in the presence of silanes in which five- or six-membered carbocycles or pyrrolidine derivatives were afforded up to 86% ee by the use of (2R,5R)-2,5-dimethyl-1-phenylphospholane as a monodentate chiral ligand was investigated. The reaction course of this asymmetric cyclization can be explained for by two possible mechanisms: one in which the cyclization proceeds via a pi-allylnickel intermediate to produce a cyclized product having an internal olefin in the side chain, and one in which the cyclization proceeds via a sigma bond metathesis of silane and the nickel-oxygen bond of oxanickelacycle to produce a cyclized compound having a terminal olefin and/or an internal olefin in the side chain. It was speculated that both of these mechanisms operate in this asymmetric cyclization depending upon the nature of silanes and the reaction conditions.

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PubMed2002

Ruthenium-catalyzed ROM-RCM of cycloalkene-yne.

[formula: see text] ROM-RCM (ring-opening and ring-closing metatheses) of cycloalkene-yne was demonstrated using a second-generation ruthenium complex. When cycloalkene bearing the alkyne moiety at the C-1 position was reacted with a ruthenium-carbene complex under an atmosphere of ethylene, ROM-RCM proceeded smoothly to give bicyclic compound and/or dimeric compound in good yields.

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PubMed2002

Novel Catalytic CO(2) Incorporation Reaction: Nickel-Catalyzed Regio- and Stereoselective Ring-Closing Carboxylation of Bis-1,3-dienes.

Novel nickel-catalyzed carboxylation of bis-1,3-dienes using carbon dioxide (CO2) was investigated. In the presence of catalytic amounts of Ni(acac)2 and PPh3, various bis-1,3-dienes smoothly reacted with CO2 and an organozinc reagent (Et2Zn, Me2Zn, or Ph2Zn) under mild conditions. This catalytic carboxylation process was accompanied by carbocyclization of bis-1,3-diene followed by alkylation by an organozinc reagent to afford cyclic carboxylic acid derivatives in high yields with high regio- and stereoselectivities.

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PubMed2002

Nickel-catalyzed intermolecular coupling of 1,3-dienes and aldehydes via transmetalation of nickelacycles with diisobutylaluminum acetylacetonate.

Intermolecular coupling reactions of 1,3-dienes and aldehydes via transmetalation of nickelacycle intermediate with (i)Bu(2)Al-acac were investigated. In the reactions, a linear adduct or a branched adduct was produced, depending upon the nature of 1,3-dienes and aldehydes, via two nickelacycles that were relatively stable among the four possible nickelacycles because of the equilibrium with pi-allynickel forms.

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PubMed1997

Total Syntheses of (-)-Mesembrane and (-)-Mesembrine via Palladium-Catalyzed Enantioselective Allylic Substitution and Zirconium-Promoted Cyclization.

4-Arylhexahydroindole derivatives 5 were synthesized from 2-arylcyclohexenyl allylamine derivatives 4, which have a large protecting group on nitrogen, using zirconium-promoted cyclization. Reaction of 4e with Cp(2)ZrBu(2), followed by treatment with MeMgBr and then O(2), gave 2a in 63% yield by a one-pot reaction, since the approach of O(2) to zirconium was prevented by the aryl group. The total syntheses of (+/-)-mesembrane and (+/-)-mesembrine were achieved starting from 2a. To synthesize these natural products in a chiral form, the starting allylamine derivative 24 (80% yield, 86% ee, recrystallized from MeOH, 99% ee with 79% recovery) was prepared from allyl carbonate 22a and N-tosylallylamine 23 using palladium-catalyzed asymmetric amination in the presence of (S)-BINAPO as a chiral ligand. (-)-Mesembrane and (-)-mesembrine were synthesized from this allylamine 24.

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PubMed1996

Highly Stereocontrolled Cyclopropanation by the 1,3-Elimination of a Bis(tributylstannyl)propanol Derivative.

The highly stereoselective ring closure of gamma-hydroxystannyl derivative was realized. The aldol reaction of methyl bis(tributylstannyl)propionate (2) with aldehyde 5 proceeds stereoselectively to give (gamma-hydroxypropyl)stannane 6, and the cyclopropanation reaction of aldol product 6 proceeds smoothly in a highly stereoselective manner presumably via a W-shape transition state. The stannyl group on the cyclopropane ring can be converted into various electrophiles with a retention of configuration. As a result, various stereocontrolled 1,2,3-trisubstituted cyclopropanes can be obtained in high yields.

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