Keiichiro Hatano

Stereoselective synthesis of dihydrofurans under phase-transfer catalyzed conditions

Abstract Treatment of cyclic or acyclic α-haloenones with various carbon nucleophiles involving active methylene functions afforded the corresponding dihydrofurans in a stereoselective manner with good to high yields. This reaction system can provide a general and practical methodology for the construction of dihydrofuran rings.

Synthesis and application of new chiral bidentate phosphine, 2,7-di-tert-butyl-9,9-dimethyl-4,5-bis(methylphenylphosphino)xanthene

Abstract New optically active bidentate phosphines, (S,S)- and (R,R)-2,7-di-tert-butyl-9,9-dimethyl-4,5-bis(methylphenylphosphino)xanthenes ( (S,S)- 1 and (R,R)- 1 ), were prepared through resolution of the corresponding phosphine oxides using (R,R)-(−)-dibenzoyl-tartaric acid and a preliminary experiment on asymmetric synthesis using an allyl substrate proved the utility of the new bidentate phosphines.

New monodentate chiral phosphine 2,6-dimethyl-9-phenyl-9-phosphabicyclo[3.3.1]nonane(9-PBN): Application to asymmetric allylic substitution reaction

Abstract New monodentate chiral phosphines, (+)- and (−)-2,6-dimethyl-9-phenyl-9-phosphabicyclo[3.3.1]nonanes ((+)- and (−)-9-PBNs), were prepared from 1,5-dimethyl-1,5-cyclooctadiene, and their application to the asymmetric allylic substitution reaction proved the utility of 9-PBNs as chiral phosphine ligands.

Flavanones from Iris tenuifolia

Abstract From the underground part of Iris tenuifolia several flavonoids have been isolated. Six new flavanones have been characterized by high resolution mass spectrometry (HR-MS), and 1 H and 13 C NMR as 5,2′,3′-trihydroxy-6,7-methylenedioxyflavanone, 5,2′-dihydroxy-6,7-methylenedioxyflavanone, 5,2′,3′-trihydroxy-7-methoxyflavanone, 5,3′-dihydroxy-7,2′-dimethoxyflavanone, 3,5,2′,3′-tetrahydroxy-7-methoxyflavanone and 3,5,3′-trihydroxy-7,2′-dimethoxyflavanone. The crystal and molecular structure of the first flavanone has been established by X-ray crystallography.

Asymmetric allylic substitution reactions of 2-substituted 2-cycloalkenyl carbonates using 9-PBN coordinated palladium

Abstract 2-Substituted 2-cycloalkenyl carbonates are suitable substrates for asymmetric allylic substitution reaction using 9-PBN coordinated palladium, producing the allylic substituted products with high enantiomeric excess.

Complexation equilibria and structures of dimethyltin (IV) complexes with N-methyliminodiacetate, pyridine-2,6-dicarboxylate, ethylenediamine-N,N′-diacetate and ethylenediamine-N,N,N′,N′-tetraacetate

Abstract The complexation equilibria of the dimethyltin (IV) ion with N -methyliminodiacetate (mida), pyridine-2,6-diacarboxylate (pdc), ethylenediamine- N , N ′-diacetate (edda) and ethylenediamine- N , N , N ′, N ′-tetraacetate (edta) have been investigated in aqueous solution at 25.0 °C and I = 0.1 mol dm −3 ((H, Na)NO 3 ) by potentiometric measurements. The overall stability constants B pqr for [(SnMe 2 ) p H q L r ] (2 p + q − nr ) + ( n = 2 for L = mida, pdc, edda; n = 4 for L = edta) defined as [[(SnMe 2 ) p H q L r ] 2 p + q − nr ) + ] [SnMe 2 2+ ] − p [H + ] − q [L n − ] −1 are evaluated as follows: log β 1−11 = 2.53(3), log β 101 = 9.625(4) and log β 112 = 20.73(4) for L = mida; log β 101 = 10.533(6), log β 111 = 12.65(5) and log β 112 = 17.69(3) for L = pdc; log β 101 = 12.412(8), log β 111 = 15.75(3), log β 112 = 24.12(4) and log β 122 = 30.87(4) for L = edda; log β 2−21 = 4.75(1), log β 2−11 = 10.44(2) and log β 201 = 15.41(2) for L = edta. The crystal structures of [SnMe 2 (mida)(H 2 O)] · H 2 O, [SnMe 2 (pdc)(H 2 O)] · H 2 O, [SnMe 2 (edda)] and [(SnMe 2 ) 2 (edta) (H 2 O) 2 ] · H 2 O have been determined by X-ray crystal structure analyses. The mida and pdc complexes have a dimeric structure which consists of distorted pentagonal-bipyramidal tin units with two methyl groups in the axial position. The edda complex has a distorted octahedral monomer structure with two methyl groups in the cis position. The edta complex consists of a polymer structure with spanning edta ligands in which each tin unit has a geometry quite analogous to those of the mida and pdc complexes. The preference in geometry of the dimethyltin(IV) complexes is discussed in terms of the effects of the bound ligands. The dimethyltin(IV) complexes formed in aqueous solution have been characterized on the basis of the molecular structures in the crystals and the values of the stability constants and p K a .

An efficient synthesis of C20–C25 building blocks for calyculin A

Abstract The C 20 –C 25 building blocks 2 and 3a for calyculin A, a protein phosphatase inhibitor, have been efficiently prepared from L-malic acid utilizing the Grignard reaction of the Weinreb amides 8 and 14 , followed by stereoselective reduction of the ketones 9 and 15 , respectively, as the key steps.

Synthesis of chiral tetrahydroisoquinoline-derived β-amino alcohols and their application to asymmetric reaction

Three chiral 1,2,3,4-tetrahydroisoquinoline-derived β-amino alcohols were synthesized by using the Ru-catalyzed asymmetric transfer hydrogenation of 6-methoxy-1-(2-methoxyphenyl)-3,4-dihydroisoquinoline as the key reaction. The ability of the synthesized β-amino alcohols as chiral ligands was evaluated in the addition of diethylzinc to benzaldehyde.

Stereoselective synthesis of (S)-(+)-lycoperdic acid through an endo selective hydroxylation of the chiral bicyclic lactam enolate with MoOPH

Abstract Efficient synthesis of (S)-(+)-lycoperdic acid has been achieved by use of the stereoselective hydroxylation of the enolate derived from the bicyclic lactam 3 with the molybdenum oxidizing reagent, MoOPH (MoO5·Py·HMPA, oxodiperoxymolybdenum(pyridine)(hexamethylphosphoric triamide)), as a key step.

A novel diterpenoid with a rearranged neoclerodane skeleton from Salvia leucantha CAV.

A new diterpenoid with a rearranged neoclerodane skeleton, spiroleucantholide (compound “S1”), along with four known diterpenoids—salvifaricin (compound “S2”), isosalvipuberulin (compound “S3”), salvileucantholide (compound “S4”), and salviandulin E (compound “S5”)—was isolated from the aerial parts of Salvia leucantha CAV.. The structures were established by spectroscopic methods, including the X-ray analysis of spiroleucantholide (S1).