Halovinylsulfones 4 . Synthesis and some reactions of 2-phenylsulfonyl-2-propenyl isothiocyanate

The title compound, isothiocyanate 2 , was obtained in good yield from the reaction of α-chloromethylvinyl-sulfone 1 with lead thiocyanate. The isothiocyanate 2 was reacted with aromatic amines to give 2-amino-5,6-dihydro-4H-1,3-thiazines 3 in good to moderate yields. The formation pathways are discussed.     

Multimetalated carboxylates in a filament in-beam electron impact mass spectrometer

An in-beam electron impact mass spectrometer has been modified using a tungsten or platinum filament as an in-beam probe. With this simple device, metalated organic molecular ion peaks of strong intensities are observed under electron impact conditions. New cluster ions, [(CH₃CO₂)_mLi_n]⁺ are detected, where m=3-6 and n=3, 4. Sodium and potassium acetates give stable dimetalated carboxylate ions, and less stable carboxylate ions are formed from benzoates.     

Highly enantioselective copper-catalyzed conjugate addition of diethylzinc to nitroalkenes

Copper-catalyzed asymmetric conjugate addition of diethylzinc to nitroalkenes using new chiral monodentate phosphoramidite ligands proceeds with high enantioselectivity up to 99% ee. [reaction: see text]     

Vectorial electron relay at ITO electrodes modified with self-assembled monolayers of ferrocene-porphyrin-fullerene triads and porphyrin-fullerene Dyads for molecular photovoltaic devices

Systematic series of indium tin oxide (ITO) electrodes modified covalently with self-assembled monolayers (SAMs) of ferrocene-porphyrin-fullerene triads and porphyrin-fullerene dyads were designed to gain valuable insight into the development of molecular photovoltaic devices. The structures of SAMs on ITO have been investigated by UV/Vis absorption spectroscopy, atomic force microscopy, and cyclic voltammetry. The photoelectrochemical and photophysical (fluorescence lifetime and time-resolved transient absorption) properties were also determined. The highest quantum yield of photocurrent generation (11 %) among donor-acceptor linked systems which are covalently attached to the surface of ITO electrodes was achieved with SAMs of ferrocene-zinc porphyrin-fullerene linked triad on ITO electrodes. The quantum yields of photocurrent generation correlate well with the charge-separation efficiency and the lifetime of the charge-separated state of the porphyrin-fullerene linked systems in solution. These results provide valuable information for the construction of photonic molecular devices and artificial photosynthetic systems on ITO electrodes.     

Synthesis of phenanthro[b]thiophenes

All isomers of the parent phenanthro[b]thiophenes, namely, phenanthro[1,2-b]thiophene, phenanthro-[2,1-b]thiophene, phenanthro[2,3-b]thiophene, phenanthro[3,4-b]thiophene, phenanthro[3,4-b]thiophene, phenanthro[4,3-b]thiophene and phenanthro[9,10-b]thiophene have been synthesized.     

Reduction of carbonyl compounds via hydrosilylation: V. Synthesis of optically active allylic alcohols via regioselective asymmetric hydrosilylation

Regioselective asymmetric reduction of prochiral α,β-unsaturated ketones to optically active allylic alcohols was performed via hydrosilylation catalyzed by a rhodium(I) complex with (+)-BMPP, (+)-DIOP and (?)-DIOP as chiral ligands. The allylic alcohols with optical purity up to 69% e.e. were obtained in good yields. The extent of asymmetric induction was found to depend on the stereo-electronic matching of the chiral ligand, ketone and hydrosilane employed. In the asymmetric reduction of (R)-carvone, leading to carveol, the extent of asymmetric induction was found to depend markedly on the ligand/rhodium ratio. Either trans-(5R,1S)-carveol or cis-(5R,1R)-carveol was obtained with good stereoselectivity by using (?)-DIOP or (+)-DIOP as chiral ligand, and it turned out that the chiral center present in carvone had only a slight influence on the asymmetric induction by the chiral catalysts.     

The reactions of hydrosilanes with trifluoropropene and pentafluorostyrene catalyzed by ruthenium, rhodium and palladium complexes

The reactions of hydrosilanes with trifluoropropene (TFP) and pentafluorostyrene (PFS) catalyzed by Ru₃(CO)₁₂ or RhCl(PPh₃)₃ give β-R_f-vinylsilane (1) and/or β-R_f-ethylsilane (2) (R_f = perfluorocarbon group). The 1/2 ratio is highly dependent on the nature of hydrosilane used. The ruthenium catalyst favors the formation of 1 compared with the rhodium catalyst. Neither -R_f-vinylsilane nor -R_f-ethyl-silane was formed at all. Possible mechanisms which can accommodate characteristic features of these reactions are discussed. The hydrosilylation of TFP with dichloro-methylsilane catalyzed by PdCl₂(PhCN)₂/2PPh₃ gives the -adduct (9a) exclusively, and this is transformed to the corresponding dialkoxysilanes, silane diol, oligosilane diols and cyclic oligosiloxanes.     

Novel [2 + 2 + 2 + 1] cycloaddition of enediynes catalyzed by rhodium complexes

[reaction: see text] The first Rh-catalyzed intramolecular [2 + 2 + 2 + 1] cycloaddition reaction of enediynes and CO is reported. This novel higher order cycloaddition process gives the corresponding 5-7-5 ring systems in high yield and selectivity. This process is another significant addition to the arsenal of cycloaddition-based synthetic methods, which provide powerful tools for rapid and efficient construction of complex polycyclic systems.     

Syntheses of N,N′-Bis(salicylideneiminoethyl)oxamidatodicopper(II), N,N′-Bis(salicylideneiminoisopropyl)-oxamidatodicopper(II), and N,N′-Bis(2-pyridylideneiminopropyl)oxamidatodicopper(II) Nitrate and Corresponding Perchlorate

Reactions of coordinated functional groups were carried out as follows: The product formed by reaction of A-1a

1 The four new complexes are shown as A-3a, A-3b, B-3a, and B-3b (cf. Fig. 1), and other related complexes are shown as A-1a, A-1b, A-2a, A-2b, B-n, B-1, B-4, and B-5 (cf. Fig. 2)

or A-1b with copper(II), reacts with salicylaldehyde to give A-3a or A-3b, respectively. And the product formed by reaction of B-1 with copper(II), reacts with pyridine-2-aldehyde to give B-3a or B-3b. The four binuclear copper(II) complexes thus isolated as the new compounds have been characterized by elemental analyses, u.v. and i.r. spectra, magnetic susceptibility, and electronic conductivity measurements. Attempts to exchange the reactants with one another were unsuccessful.     

Organometallic chemistry and homogeneous catalysis of Rh and Rh-Co mixed metal carbonyl clusters

The reactions of hydrosilane and/or alkyne as well as isonitriles with rhodium and rhodium cobalt mixed metal carbonyl clusters, e.g., Rh₄(CO)₁₂ and Co₂Rh₂(CO)₁₂, are studied. Novel mixed metal complexes, e.g., CoRh(CO)₅ (HCCBu ⁿ ), (R₃Si)₂Rh(CO) _n Co(CO)₄, Rh(R–NC)₄Co(CO)₄, Co₂Rh₂(CO)₁₀(HCCR), and Co₂Rh₂(CO)₉(HCCBu ⁿ ), are synthesized and identified. The catalytic activities of these rhodium and rhodium-cobalt mixed metal complexes are examined in hydrosilyation, silylformylation, and novel silylcarbocyclization reactions. Possible mechanisms for these reactions are proposed and discussed.