Yoshinori Naruta

Enantioselective oxidation of sulfides catalyzed by iron complexes of chiral “twin coronet” porphyrins

Abstract Ferric porphyrins bearing chiral binaphthalene moieties on their both faces catalyze asymmetric oxidation of sulfides with iodosobenzene as an oxidant in moderate to good optical and chemical yields. Enantiomeric excesses (e.e.) were markedly improved in 2–3 times by the addition of 1-methylimidazole. The mechanism of oxidation and chiral induction are discussed.

NMR study on transmetaliation reaction between allyltins and SnCl4

Abstract Various allyltrialkyltins react with a typical Lewis acid, SnCl 4 , at −50°C. The tin compounds with a less substituted allyl group immediately and cleanly give The corresponding allyltrichlorotins via transmetallation through S E 2 pathway, while more substituted ones give precipitates. Crotyltributyltin and SnCl 4 first afford (1-methyallyl)trichlorotin, which then isomerizes to crotyltrichlorotin. Electron deficiency of The pentadienyl moiety in pentadienyltrichlorotin is evident as is the case with allyltrichlorotins. Highly fluxional structure of ( Z )-pentadienyltrichlorotins is revealed. Interaction between some allyltins and BF 3 · OEt 2 is also demonstrated.

meso-perfluorination of porphyrins with N-fluoropyridinium triflate

Abstract Octaethylporphyrin was perfluorinated at its meso -positions with N -fluoropyridinium triflate in 67% of a total yield.

Lewis acid mediated allylation of 2-alkanoyl-1,4-quinones with allylsilane and allylstannane☆

Abstract Allyltrimethylstannane reacts uith 2-alkanoyl-1,4-quinones regioselectively to afford conjugate addition products which can be derived to 2-alkanoyl- 3-allylhydroquinone diacetate, while allyltriphenylsilane reacts with the quinone to give naphthofuran.

Cytochrome P-450 modelling oxygenation of olefins within the space-restricted cavity of iron “binap porphyrin”: Rate enhancement in the presence of imidazole

Abstract In the presence of 1,5-diphenylimidazole, iron porphyrin modified by binaphthyl groups on one side exhibited increased rate in epoxidation of olefins and shape selective oxidation. Spectrophotometric study supports the inhibition of the formation of the six-coordinated bisimidazole complex. Oxidation within the modified cavity is proposed.

Remarkable effects of metal ions and axial bases on catalytic and asymmetric oxidation of simple olefins with a 'twin-coronet' porphyrin

Abstract Effect of central metals and oxidants on the catalytic and asymmetric epoxidation of simple olefins was evaluated with a chiral binaphthalene-linked twin-coronet porphyrin catalyst, whose Mn derivative gave superior ees of resultant epoxide than the corresponding Fe derivative.

Syntheses of (±)-aklavinones : Application of the stereocontrolled “zipper” bicyclo cyclization reaction

Abstract Efficient syntheses of(1+-)-aklavinones; (±)-aklavinone (1), (±)-auramycinone (2), and (±)-13-methylaklavinone (3), are described. A key process of the tetracyclic ring construction in these syntheses is ia stereocontrolled “zipper” bicyclo-cyclization using a KH-Kryptofix 222 (4,7,13,16,21,24-hexaoxa-1.10-diazabicyclo [8.8.8]hexacosane) cryptate as a base. The reaction mechanism is discussed, too

An efficient asymmetric synthesis of 11-deoxyanthracyclinone

Abstract (7S,9S)-(+)-11-Deoxyanthracyclinone 4b is synthesized in a high optical yield (96 %ee) by the Sharpless asymmetric epoxidation of the tetracyclic allylalcohol 9, which is readily prepared via the tandem Michael/Diels-Alder reaction.

The excited-state dynamics of acetyl-and anthraquinone-linked α,α,α,α-meso-tetra (2-aminophenyl) porphyrin derivatives (XTAPPAc and XTAPPAQ) studied by picosecond laser photolysis in acetonitrile at room temperature

Abstract Upon picosecond laser photolysis of XTAPPue5f8Ac, it is concluded that the lowest excited singlet state is the locally excited singlet state of the porphyrin moiety. For XTAPPue5f8AQ, however, there exists a rapid interconversion between the locally excited singlet state of the porphyrin moiety and the charge-separated singlet state produced by an electron transfer from the porphyrin to anthraquinone moieties, although their center-tocenter distance is 8.8 A.

Lewis acid mediated claisen-type rearrangement of aryl dienyl ethers

Abstract In the presence of BF 3 ·.OEt 2 , aryl dienyl ethers were rearranged under mild conditions to afford dienyl phenols in good yields.