Yoshiro Masuyama

Palladium-catalyzed carbonyl allylation by 2-(hydroxymethyl)acrylate derivatives: synthesis of α-methylene-γ-butyrolactones

Ethyl 2-(Hydroxymethyl)acrylate derivatives serve as reagents for 2-ethoxycarbonylallylation of carbonyl compounds using PdCl2(PhCN)2-SnCl2 system to produce α-methylene-γ-butyrolactones diastereoselectivity.

Chemoselective oxidation with molybdenum catalyst-t-butyl hydroperoxide

Abstract Benzyltrimethylammonium tetrabromooxomolybdate is an excellent chemoselective catalyst to oxidize secondary alcohols to ketones, primary alcohols to esters, and aldehydes to acids or esters with t-butyl hydroperoxide.

Straightforward synthesis of five-membered metallacycloallenes: 1-Zirconacyclopenta-2,3-diene compounds derived from 1,3-enynes

A five-membered metallacycloallene complex, 1-zirconacyclopenta-2,3-diene, was prepared from low-valent zirconocene and 2,4-bis(trimethylsilyl)but-1-en-3-yne. The complex reacted with carbonyl compounds to afford alkynyl alcohols after hydrolysis via C=O insertion into Zr–C bond. Similarly, nitriles inserted into the Zr–C bond to give the corresponding ketones after hydrolysis. The insertion of C=O and CN selectively took place at zirconium-sp3 carbon of the metallacycle.

Diastereoselectivity in carbonyl allylation by allylic carbonates using PdCl2(PhCN)2-SnCl2 system

Abstract Allylic carbonates were more active than the corresponding allylic acetates in carbonyl allylation using PdCl 2 (PhCN) 2 -SnCl 2 , and the carbonyl allylation by (E)-crotyl carbonate at 10 °C exhibited opposite diastereo-selectivity (anti-selectivity) to that by (E)-crotyl acetate at 60 ° C.

Palladium-catalyzed carbonyl allylation by allylic alcohols with SnCl2. A solvation-controlled diastereoselection

Diastereocontrol in the allylation of benzaldehyde by (E)-but-2-en-1-ol using catalyst PdCl2(PhCN)2 and SnCl2 was achieved by the choice of polar solvents; use of DMSO at 25 °C led to syn selection, while anti selection was found at -10 °C in THF. The addition of 3–10 equivalents of H2O in any solvent enhanced the selectivities, and the control of the amount of H2O in DMSO permitted both syn selection (a small amount of H2O) and anti selection (a large amount of H2O).

Charge reversal of electrophilic π-allylpalladium intermediates; carbonyl allylation by allylic acetates with PdCl2(PhCN)2–SnCl2

Carbonyl allylation by stable allylic acetates with Pd0–SnCl2 occurred regio-, chemo-, and diastereoselectively to afford the corresponding homoallylic alcohols.

Syntheses and characterization of homodinuclear manganese and cobalt complexes bridged by a hemiacetal or by an acetato group in a μ-(η2:η1) bridging mode

Abstract The complex [Mn2(BPMAPS)(μ-OAc)2(hemi)]PF6 (1), where hemi is the hemiacetal group, methoxy(2-pyridyl)methoxo, was prepared from bis[3-(2-pyridylmethyleneamino)phenyl] sulfone (BPMAPS), 2-pyridinecarbaldehyde, and manganese(II) acetate in methanol. The complexes Mn2(BPMAPS)(μ-OAc)2(μ-1,1-OAc)(η1-OAc) (2) and Co2(BPMAPS)(μ-OAc)2-[μ-(η2:η1)OAc](η1-OAc) (3) were prepared from manganese(II) acetate and cobalt(II) acetate, respectively, with BPMAPS in methanol. All three complexes were characterized by elemental analysis, FT-IR, MS, UV–Vis spectroscopy, and X-ray crystallography. The manganese ions of complex 1 are bridged by a hemiacetal through the oxygen atom of the alkoxo with the nitrogen atom of the pyridine group coordinating to one of the manganese atoms. The metal ions of complexes 2 and 3 are bridged by acetato groups in μ-1,1 or μ-η2:η1 modes, respectively.

γ-Syn-selective carbonyl allylation by 1-Bromo-2-butene with tin(II) iodide and tetrabutylammonium bromide

Abstract ( E )-rich 1-Bromo-2-butene preferentially caused γ-syn-allylation of aldehydes with tin(II) iodide and tetrabutylammonium bromide (or iodide) in THF-H 2 O or 1,3-dimethyl-2-imidazolidinone-H 2 O to produce 1-substituted syn-2-methyl-3-buten-1-ols.

1,3-bis(phenylsulfonyl)butadienes: synthesis applying knoevenagel-type condensation and michael-type addition-cyclization with enamines

Abstract Knoevenagel-type condensation of 1,3-bis(phenylsulfonyl)propene with aldehydes provided electron-deficient dienes, 1,3-bis(phenylsulfonyl)butadiene derivatives, and one of these dienes, 4-[3,4-(methylenedioxy)]phenyl derivative was applied to Michael-type addition with enamines to form six-membered ring systems.

Surface properties of supported molybdenum catalysts

Abstract Heterogeneous catalysts consisting of highly dispersed supported molybdenum have been investigated. Hexacarbonylmolybdenum(0) catalysts supported on TiO2, Al2O3, ZrO2, MgO, and SiO2 were characterized by temperature-programmed decomposition (TPDE), XPS, and catalytic activity for CO shift reaction, metathesis, and hydrogenation of alkenes. Mo catalyst supported on TiO2 showed higher catalytic activity than that of the Mo catalysts on other supports. The TPDE spectrum of Mo(CO)6 on TiO2, which was pretreated at 773 K, showed two-stage decomposition peaks due to the elimination of CO ligands with very little evolution of H2, which resulted in a lowvalent catalyst. After the first stage of TPDE, Mo(CO)3 species were formed on TiO2. Those species gave higher catalytic activity for CO shift reaction at 403 K, but not for hydrogenation and metathesis. Metathesis of propene at 323 K and hydrogenation of 1,3-butadiene at 273 K showed higher activity only after the second stage. Those catalytic activities are one or two orders of magnitude higher than those of corresponding oxide catalysts. When the catalyst was pretreated at 600–773 K, slight oxidation of Mo occurred due to the presence of hydroxyls of TiO2; this suppresses the catalytic activities for CO shift reaction and hydrogenation. However, the activity of metathesis increased with increasing evacuation temperatures. The results suggest that metathesis requires a higher oxidation state of Mo than do CO shift reaction and hydrogenation.