Hiroo Toi

Fluoropyrroles and tetrafluoroporphyrins

Abstract Photolysis of pyrrole-β-diazonium tetrafluoroborates gave β-fluoropyrroles. These were further converted to 1,3,5,7-tetrafluoroporphyrins, the first example of ring-fluorinated porphyrin derivatives.

Catalytic Reactions of Metalloporphyrins. Part 1. Catalytic Modification of Borane Reduction of Ketone with Rhodium(II) Porphyrin as Catalyst.

(Octaethylporphyrinato)rhodium(III) Chloride exhibits efficient catalysis in the aerobic reduction of ketones (I) with NaBH4 to give the alcohols (II).

Novel chiral porphyrins with C2 symmetry

Abstract Described is the preparation of chiral octaethylporphyrin derivatives having two 2-substituted naphthyl groups in a trans orientation at the 5- and 15-meso positions and formyl or hydroxymethyl or alkoxymethyl group derived therefrom at the 10-meso position. One of the derivatives has been successfully resolved into enantiomers by means of HPLC.

5,15-Bis(8-quinolyl)- and -bis(2-pyridyl)octaethylporphyrin: preparation, stabilities of atropisomers, and metal-ion binding properties

Abstract 5,15-Bis(8-quinolyl)octaethylporphyrin gives stable and isolable atropisomers, but the 5,15-bis(2-pyridyl) analog does not. The quinolyl group has no interaction with the central metal, but it readily binds external metal. Also described is the novel dimerization of Rh(III) complex induced by intramolecular 2-pyridyl ligands.

Synthesis of β-trifluoromethylpyrroles

Abstract The β-trifluoromethylpyrroles have been synthesized by the modified Knorr condensation in strong acid media.

Molecular recognition in the ternary systems of a trifunctional chiral metalloporphyrin, amino esters, and HPLC adsorbent

Abstract A new chiral porphyrin was prepared by the coupling of two different types of dipyrromethanes in the presence of 2-hydroxynaphthaldehyde. Racemic ClRh(III) complex derived forms diastereomeric 1:1 adducts with L-amino acid methyl esters. The HPLC behaviors of diastereomers were discussed in terms of molecular recognition in the ternary system of the present trifunctional metalloporphyrin, an amino ester, and HPLC adsorbent.

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.

Synthesis of 1-fluoro-1-demethylmesoporphyrin-IX

Total syntheses of 1-fluoro-1-demethylmesoporphyrin-IX and its metal complexes are described. The iron(III) complex forms stable reconstituted myoglobin. Paramagnetic 19 F-nmr spectra of metalloporphyrins were measured for the high and low spin states of the iron(III) complexes

Polar host–guest interactions. Solubilization of some polar compounds with lipophilic calix[6]arenes containing polar groups in apolar media

Alkylation of three of the six hydroxy groups in calix[6]arene (2) with 1-bromo-7,7-di(ethoxycarbonyl)pentacosane (3) followed by hydrolysis and subsequent condensation with NH3 gives rise to a hexa-amide derivative (6); the structural formula refers to a mixture of regioisomers of unknown composition. 1-Ethyl-4-methoxycarbonylpyridinium iodide (12) and formamide (HCONH2) as polar guests are solubilized in apolar organic solvents such as hexane and CCl4via host–guest (1:1) complex formation with (6) as a lipophilic polar host. The absorption maximum at 365 nm of (12) thus solubilized indicates that the binding site of (6) for (12) is relatively polar. The solubilization of (12) and HCONH2 is discussed in terms of micro-solvation interactions of the polar core of (6) with the guests.

Preparation and optical resolution of novel 5,10-diaryloctaethylporphyrins with C2 symmetry

Abstract Zinc complex of 5,10-bis(2-hydroxynaphthyl)octaethylporphyrin was prepared by coupling tripyrrole and monopyrrole derivatives in the presence of 2-hydroxynaphthaldehyde. The chiral trans isomer and di(benzyl ether) derivative derived therefrom were successfully resolved into enantiomers by means of HPLC.