Toshikatsu Takanami

High-valent metalloporphyrin, Fe(tpp)OTf, catalyzed rearrangement of α,β-epoxy ketones into 1,2-diketones

Iron(III) tetraphenylporphyrin triflate, Fe(tpp)OTf, works as an efficient and characteristic Lewis acid catalyst in the selective rearrangement of α,β-epoxy ketones into 1,2-diketones.

METALLOPORPHYRIN-CATALYZED REGIOSELECTIVE REARRANGEMENT OF MONOALKYL-SUBSTITUTED EPOXIDES INTO ALDEHYDES

Abstract Iron(III) tetraphenylporphyrin, Fe(tpp)OTf, is an efficient catalyst for the regioselective rearrangement of simple monoalkyl-substituted epoxides into the corresponding aldehydes.

Palladium-catalyzed meso-amination and amidation of porphyrins: marked acceleration with the Ni(II) central metal ion

The preparation of meso-amino and meso-amido substituted porphyrins was easily accomplished by palladium-mediated cross-coupling reactions of meso-brominated porphyrins with amines and amides. Ni(II) introduced as a central metal ion into the substrate porphyrin markedly accelerated the cross-coupling.

Metallophthalocyanine complex, Cr(TBPC)OTf: an efficient, recyclable Lewis acid catalyst in the regio- and stereoselective rearrangement of epoxides to aldehydes

The metallophthalocyanine complex Cr(TBPC)OTf works as a highly efficient, recyclable Lewis acid catalyst for the regio- and stereoselective rearrangements of epoxides to aldehydes.

One-Pot Synthesis of meso-Formylporphyrins by SNAr Reaction of 5,15-Disubstituted Porphyrins with (2-Pyridyldimethylsilyl)methyllithium

A simple, one-pot procedure that converts 5,15-substituted porphyrins into the corresponding meso-formylated porphyrins has been developed. The method, based on a new synthetic concept for functionalized porphyrins utilizing the (2-pyridyldimethylsilyl)methyl group as a latent formyl functionality, affords the desired product in good yield and is especially appropriate for the direct formylation of free base porphyrins, which has never been achieved by known methods.

Palladium-catalyzed Kumada coupling reaction of bromoporphyrins with silylmethyl Grignard reagents: preparation of silylmethyl-substituted porphyrins as a multipurpose synthon for fabrication of porphyrin systems.

We have developed an efficient method for preparing silylmethyl-substituted porphyrins via the palladium-catalyzed Kumada cross-coupling reaction of bromoporphyrins with silylmethyl Grignard reagents. We demonstrated the synthetic utility of these silylmethylporphyrins as a multipurpose synthon for fabricating porphyrin derivatives through a variety of transformations of the silylmethyl groups, including the DDQ-promoted oxidative conversion to CHO, CH(2)OH, CH(2)OMe, and CH(2)F functionalities and the fluoride ion-mediated desilylative introduction of carbon-carbon single and double bonds.

Anodic oxidation of 2-alkyl-2-trialkylsilyl-1, 3-dithianes a facile preparation of acylsilanes

Abstract Acylsilanes can easily be prepared by the anodic oxidation of 2-alkyl-2-trialkylsilyl-1, 3-dithianes with a platinum anode in wet acetonitrile. This electrochemical reaction provides a general and convenient access to aroyl, saturated and α, β-unsaturated acylsilanes.

A novel synthetic intermediate in β-lactam chemistry: an efficient preparation of cis-1,3,4-tris(trimethylsilyl)azetidin-2-one and its transformation into 4-acetoxy-3-alkylideneazetidin-2-ones

The addition of trimethylsilyl azide to cis-2,3- bis(trimethylsilyl)cyclopropan-1-one in the presence of a sodium azide/15-crown-5 catalyst gave cis-1,3,4-tris(trimethylsilyl)azetidin-2-one, which could easily be transformed into 4-acetoxy-3-alkylideneazetidin-2-ones by way of Peterson olefination followed by anodic oxidation.

Reaction of cis-2,3-bis(trimethylsilyl)cyclopropanone with β-ketophosphorus ylides: unexpected formation of furans

Abstract The reaction of cis -2,3-bis(trimethylsilyl)cyclopropanone with β-ketophosphorus ylides unexpectedly gave furans in high yields.

Regioselective β-silylation of porphyrins via iridium-catalyzed C–H bond activation

An efficient approach to meso-unsubstituted β-silylporphyrins was developed through highly regioselective Ir-catalyzed C-H activation, in the presence of HSiMe(OSiMe3)2 as the Si source, from meso-unsubstituted porphyrins. Further transformations of the silyl group, such as oxidation, halogenation, and cross-coupling reactions, could be achieved under mild conditions, demonstrating the synthetic utility of β-silylporphyrins as a multipurpose synthon for fabricating porphyrin derivatives.