Norio Mimura

Regio- and stereoselectivity in reactions of 2,3-cis- and trans-3-alkyl-2-vinylaziridines with organocopper reagents: Importance of 2,3-cis-stereochemistry in controlling selectivity

Abstract By treatment with organocopper reagents, N -activated 2,3- cis -3-alkyl-2-vinylaziridines produced exclusively ( E )-allyl amines in high yields, presumably via an anti -S N 2′ reaction pathway. On the other hand, under otherwise identical conditions, N -activated 2,3- trans -3-alkyl-2-vinylaziridines gave an 85-96:15-4 mixture of ( E )- and ( Z )-allyl amines. In reactions of certain N -activated2,3- trans -3-alkyl-2-vinylaziridines S N 2 reaction products were obtained in only 2–3% yield.

SN2′ Ring opening of aziridines bearing an α,β-unsaturated ester group with organocopper reagents. A new stereoselective synthetic route to (E)-alkene dipeptide isosteres

Regio- and stereo-selective synthesis of (E)-alkene dipeptide isosteres has been successfully achieved by exposing both (E)- and (Z)-N-(4-methylphenyl)sulfonyl-γ,δ-epimino-α,β-enoates to organocopper reagents at –78 °C for 30 min.

Palladium-catalyzed reductive ring opening with formic acid of aziridines bearing an α,β-unsaturated ester group

Abstract The palladium-catalyzed reduction of various N -arenesulfonylaziridines bearing α,β-unsaturated ester groups with formic acid and the stereochemistry of the reaction products have been investigated in detail. In all cases examined, (Z)-α,β-enoates, ( E )-α,β-enoates, and ( E )-β,γ-enoates bearing amino functionality at the δ-position were obtained. The formation of these three reduction products was taken as an indication that palladium-catalyzed isomerization occurs prior to the reduction step.

A thermodynamic preference of chiral cis-γ,δ-epimino-(E)-α,β-unsaturated esters over other stereoisomers: Synthetically useful Pd(0)-catalyzed equilibrated reactions of aziridines bearing an α,β-unsaturated ester group

Abstract A practical synthesis of chiral N -arylsulfonyl- cis - γ , δ -epimino-( E )- α , β -enoates, key intermediates for the synthesis of ( E )-alkene dipeptide isosteres via Pd(0)-catalyzed equilibrated reactions, has been successfully achieved by exposing N -arylsulfonyl-γ,δ-epimino-α,β-unsaturated esters to a catalytic amount of Pd(PPh 3 ) 4 in THF at 0 ∼ 20 °C.

(E)-stereoselective synthesis of vinylglycines from (R)-serine via organocopper–BF3 and related reagents

The stereoselective synthesis of biologically important vinylglycine derivatives by reaction of homochiral 4-methoxycarbonyl-5-vinyloxazolidin-2-ones with organocopper reagents is described; 4,5-trans-oxazolidin-2-one 6 yields (E)-vinylglycines as the major products by treatment with the ‘higher order’ cyanocuprate–BF3 reagents or trialkylzincates in the presence of cuprous cyanide, 4,5-cis-oxazolidin-2-one 10 affords only the desired (E)-vinylglycines.

Simulation of vibrational spectra of isotopic benzenes by an extended molecular mechanics method

Abstract Vibrational spectra of benzene and benzene-d6 in the gas and liquid phase have been simulated by a molecular mechanics method including the calculation of equilibrium structures, thermodynamic quantities, normal frequencies and vibrational transition probabilities. The potential parameters have been estimated by referring to the observed frequencies of benzene, benzene-d6 and 1,3,5-benzene-d3 and also to results of ab initio calculations. Four and ten independent parameters are required, respectively, for elucidating the infrared absorption and Raman intensities of these compounds in the gas and liquid phase. The infrared absorption spectrum of benzene-d1 is reproduced well by using the potential and the intensity parameters estimated for benzene and benzene-d6. The change of relative band intensities on the phase change has been elucidated in terms of the change of various intensity parameters.

Synthesis and reactivities of a novel flavoenzyme model, 5-deazaflavin with C2-symmetry

Abstract The title model compound represents a redox property of the active site of flavoenzymes and an environmental effect of the apoproteins. Its stereostructure was elucidated by 1 H-NMR spectra and energy minimum calculations. The stereoselectivity of this model was observed during the reaction with Me 2 PNPH, as NAD(P)H model.