Akio Sonoda

Reactions of ferrocenylcarbene IV. The synthesis of [3]-ferrocenophan-2-one tosylhydrazone and the thermal decomposition of its sodium salt☆

Abstract A practical synthesis of 1,1′-ferrocenediacetic acid (Va), the starting material for the preparation of [3]-ferrocenophan-2-one (VI) has been accomplished by successive reactions starting from l,l′-ferrocenedicarboxylic acid (IIIa). The synthesis of the tosylhydrazone (VII) and thermal decomposition of its sodium salt have been described. Ferrocenophane-β-carbene generated in the thermal decomposition has been suggested to be triplet.

Palladium(II)-catalysed asymmetric cyclisation of 2-allylphenols by the use of optically active β-pinene

The palladium(II)-catalysed asymmetric cyclisation of 2-(but-2-enyl)phenol (1) to optically active 2,3-dihydro-2-vinylbenzofuran (3) can be achieved in 12% optical yield by using a catalytic amount of (–)-β-pinene, while in the presence of excess of β-pinene, cyclisation of (1) does not occur.

Selective reduction of tertiary alkyl, benzyl, and allyl halides to hydrocarbons using lithium 9,9-di-n-butyl-9-borabicyclo[3.3.1]nonanate

The title 9-borabicyclo[3.3.1]nonane(9-BBN) ate complex (1) brings about selective removal of tertiary alkyl, benzyl and allyl halides to give the corresponding hydrocarbons in excellent yields without concomitant attack on secondary, primary and aryl derivatives. The reduction of cis- and trans - 4 - t - butyl - 1 - methylcyclohexyl chlorides (2) with 1 gives 4 - t - butyl - 1 - methylcyclohexanes (3) with partial inversion of configuration in cyclohexane, while that in benzene gives thermodynamically stable trans-3 predominantly. The reactions of 1,1 - dimethyl - 5 - hexenyl chloride (4) and 1,7,7 - trimethylbicyclo[2.2.1]hept - 2 - yl chloride (8) with 1 proceed with the rearrangements characteristic to a carbonium ion intermediate. The reduction of 1 - ethyl - 1 - methylpentyl chloride with 1 follows a second-order rate equation.

Crystal and molecular structures of pentane-2,4-dionato-(α, 1,2-η-tri-phenylmethyl)-palladium and -platinum

The crystal and molecular structures of [M(α, 1,2-η-CPh3)(acac)][M = Pd (3a) or Pt (3b); acac = pentane-2,4-dionate) have been determined. The unit cell of each contains enantiomers of two crystallographically independent molecules which are very similar in structure. Crystals of (3a) are triclinic, space group F, with a= 14.99, b= 13.18, c= 11.33 A, α= 101.08, β= 90.54, γ= 115.48°, and Z= 4; R= 0.050 for 5 607 independent reflections. Crystals of (3b) are triclinic, space group F, with a= 14.94, b= 11.41. c= 17.15 A, α= 120.78, β= 122.03, γ= 90.13°. and Z= 4; R= 0.045 for 5 978 independent reflections. Both structures were solved using Patterson and Fourier methods. The structures of (3a) and (3b) are very similar; each has an approximately square-planar metal atom OO′-bonded to acac and η3-benzylically bonded to the CPh3 ligand with Pd–C(α) 2.104(7), Pd–C(1) 2.158(7), Pd–C(2) 2.202 A and Pt–C(α) 2.080 (19), Pt–C(1) 2.127(20), and Pt–C(2) 2.153(23)A.

Reactions of ferrocenylcarbene—II : Reactions of ferrocenylmethylcarbene

Abstract The oxidation of acetylferrocene hydrazone with HgO and the thermal decomposition of acetylferrocene tosylhydrazone sodium salt in various solvents have been described. Both reactions proceed via ferrocenylmethylcarbene, and afford similar reaction products. In these reactions, a preferred addition reaction of the carbene to vinylferrocene is noticed. In this connection, the competitive reactivities of vinylferrocene, styrene, p -methoxystyrene and cyclohexene towards dichlorocarbene and diphenylcarbene have been measured.

Preparation and nuclear magnetic resonance studies of the dynamic processes in α, 1,2-η-triphenylmethyl- and monosubstituted-α, 1,2-η-tri-phenylmethyl-palladium and -platinum complexes

Reaction of the zerovalent palladium or platinum complexes [M2(dba)3(s)](dba = PhCHCHCOCHCHPh; s = dba or solvent) with Ph3CCl gives [{M(CPh3)Cl}n](n probably 2) which are converted into the pentane-2,4-dionates [M(CPh3)(acac)][M = Pd (3a) or Pt (3b); acac = MeCOCHCOMe] by reaction with Tl(acac). The CPh3 ligands in complexes (3a) and (3b) are η3-benzylically bound to the metal. Three different dynamic processes of progressively higher ΔG‡ are undergone by complex (3a) and have been studied by n.m.r. spectroscopy: (A), where the metal moves between two η3-positions on a single phenyl via a suprafacial [1,5]-sigmatropic shift; (B), where the metal moves from one phenyl ring to another (ΔG‡= 13.8 kcal mol–1 at 300 K); and (C), where the ends of the acac ligand also become equilibrated [after remaining distinct during processes (A) and (B)]. Process (A)[but not (B) or (C)] also occurs in (3b)(ΔG‡=ca. 6.4 kcal mol–1 at 187 K) within the accessible temperature range, but it could not be frozen out for either (3a) or (3b). A p-substituent in one phenyl ring has a small effect on the rate of process (B), but the metal shows definite site preferences and favours the phenyl bearing the more electron-releasing substituent.

‘Reversed’ regioselectivity in the reduction of epoxides with lithium 9,9-di-n-butyl-9-borabicyclo[3.3.1]nonanate

Lithium 9,9-di-n-butyl-9-borabicyclo[3.3.1]nonate reduces aromatic epoxides at the most sterically hindered position, while aliphatic epoxides are reduced at the least hindered position.

The acetoxybromination of a palladium(0) complex

Abstract [Pd 0 (PhCHCHCOCHCHPh) 2 ] n reacts with acetyl bromide to give the insoluble ; the β-diketonates derived from the bromide exhibit fluxional behaviour between two η 3 -allylic forms.

Stereoselective synthesis of E-olefins by the reaction of alkenylboranes with palladium acetate

Alkenyldialkylboranes (1) react smoothly at room temperature with Pd(OAc)2–Et3N to produce E-olefins (2) stereoselectively in moderate to high yields.

Stereoselective synthesis of 1,4-dienes and mono-olefins by methylcopper-induced cross-coupling of dialkenylchloroboranes with organic halides

Mono-olefins and 1,4-dienes have been synthesised with >99% stereochemical purity by the methylcopper-induced cross-coupling of dialkenylchloroboranes, formed from alkynes, with organic halides.