Saburo Nakanishi

Asymmetric induction in carboncarbon bond forming reactions of prochiral nucleophiles with electrophiles containing chiral iron centers

Abstract Alkylations of the chiral electrophiles CpFe(CO)(L)CH 2 Cl and CpFe(CO)(L)(CH 2 CH 2 ) + SO 3 CF 3 − (L = PPh 3 and tri( o -biphenyl)phosphite) by the prochiral nucleophiles sodium t-butyl acetoacetate and pyrrolidine cyclohexanone enamine yielded six of the eight possible alkyliron products. The two products where L was o -biphenylphosphite and t-butylacetoacetate was the nucleophile did not form, presumably because of excessive steric hindrance. Relative quantities of the two diastereomers formed in each case were easily determined from the diastereomeric resonances in their NMR spectra. Product ratios from alkylation by acetoacetate were thermodynamic, while those from alkylation by the enamine were presumed to be kinetic. The excess of one diastereomer over the other, relating in principle to an “optical yield” at the new chiral carbon center induced by the existing metal chirality, ranged from 10 to 64% depending on the nucleophile and the electrophile, but most pronouncedly, on the ligand L.

Allylation of acyl halides adjacent to (η4-diene)Fe(CO)3 fragment with allylsilanes

Abstract Acyl halides adjacent to (η 4 -diene)Fe(CO) 3 group react with allyltrimethylsilanes without catalyst to give the corresponding allyl ketones in high yields.

Conjugate addition of allylic groups to α,β-unsaturated carbonyl compounds via (η3-allyl)Fe(CO)2NO complexes

Abstract (η 3 -Allyl)Fe(CO) 2 NO complexes undergo conjugate addition to α,β-unsaturated carbonyl compounds to give the corresponding δ,ϵ-unsaturated carbonyl compounds in good yields. The reaction of (η 3 -1-or 2-trimethylsiloxyallyl) Fe(CO) 2 NO complexes with α,β-unsaturated ketones affords 1,6- or 1,5-diketones, respectively. (η 3 -1-Acetonylallyl)Fe(CO) 2 NO complexes also react with α,β-unsaturated carbonyl compounds to give 1,8-dicarbonyl compounds. The mechanisms and reactivity of these conjugate addition reactions are discussed.

Separation and characterization of diastereomeric (η4-diene)Fe(CO)3 complexes containing chiral amide groups

Abstract Diastereomeric (η 4 -N-substituted-2,4-hexadienamide)Fe(CO) 3 complexes having chiral amide groups are separated and characterized. Among the complexes, the amide complexes derived from (3R)- and (3S)-3-amino-hexahydro-2H-azepin-2-one are the most easily separated by fractional crystallization and column chromatography.

Preparation of (η3-allyl)Fe(CO)2NO complexes via ring-opening of alkenyloxiranes and their reactivities

Abstract The reaction of alkenyloxiranes with Bu 4 N[Fe(CO) 3 NO] in the presence of acetyl chloride and pyridine gave [ η 3 -1-(acetoxymethyl)allyl]-Fe(CO) 2 NO complexes. These complexes reacted regio- and stereoselectively with carbon nucleophiles to give 3-substituted 4-acetoxy-1-butene derivatives.

A novel route to δ,ε-unsaturated-α-ketocarboxylic acid esters via ring opening of 6-trimethylsilylmethyl-5,6-dihydro-4H-1,2-oxazines

6-Trimethylsilylmethyl-5,6-dihydro-4H-1,2-oxazines, which are prepared by the reaction of α-halogeno-oximes with allylsilanes in the presence of anhydrous sodium carbonate, are converted into δ,Iµ-unsaturated-α-ketocarboxylic acid esters by the action of mineral acids.

Preparation and resolution of (η4-1,3-dienecarboxylic acid)Fe(CO)3 complexes

Abstract ( η 4 -1,3-dienecarboxylic acid)Fe(CO) 3 complexes 1 were prepared, starting from a Horner-Emmons reaction of α,β-unsaturated aldehydes, followed by complexation with Fe(CO) 5 and hydrolysis of the ester groups. Reaction of 1 with ( S )-2-octanol gave a mixture of diastereomeric esters which can be easily separated by column chromatography. Enantiomerically pure ( η 4 -1,3-dienecarboxylic acid)Fe(CO) 3 complexes were obtained by hydrolysis of the esters thus separated without racemization and decomposition of the complexes.

1,3-Asymmetric induction by planar chiral (η4-diene)Fe(CO)3 complexes in Diels-Alder reaction

Abstract The Diels-Alder reaction of l,3-dienes with α,β-unsaturated ketones adjacent to planar chiral ( η 4 -1,3-diene)Fe(CO) 3 complexes in the presence of Lewis acid proceeded diastereoselectively. The dienophiles reacted with cyclopentadiene to give the endo adducts stereoselectively. The Lewis acid affected remarkably the diastereoselectivity in the reaction.

Functionalization of η4-Dienetricarbonyiron Complexes: A Facile Route to η4-Dienetri-Carbonyliron Complexes Bearing Carbonyl Groups VIA Darzens-Nenitzescu Reaction

Abstract The asymmetric Darzens-Nenitzescu reaction of acyl chloride adjacent to planar chiral (η4-diene) Fe(CO)3 fragment with alkenes in the presence of Lewis acid afforded (η4-diene) Fe(CO)3 complexes bearing β-chloroketones and unsaturated ketones in good yields.

Radical chain ligand substitution of [(η5-RC5H4)2Fe2(CO)4] with isocyanides induced by Et3B

Reaction of [(η5-RC5H4)2Fe2(CO)4] with isocyanides in the presence of a catalytic amount of triethylborane results in the selective monosubstitution of the CO ligand with the isocyanide; a radical chain process is proposed for the reaction.