Synthesis of acetylglycosylated metalloporphyrins and their catalysis for cyclohexane oxidation with PhIO under mild conditions

Tetrakis[2-(2,3,4,6-tetraacetyl-beta-D-glucopyranosyl)-1-O-phenyl]porphyrin (T(o-glu)PPH2) and tetra[3-(2,3,4,6-tetraacetyl-beta-D-glucopyranosyl)- 1- O-phenyl]porphyrin (T(m-glu)PPH2) were synthesized from the reaction of pyr role with ortho-acetylglycosylated benzaldehyde and meta-acetylglycosylated benzaldehyde, respectively, by Lindsay's method. These free acetylglycosyl ated porphyrins were metallized into acetylglycosylated metalloporphyrins, chloro[tetra(o-2,3,4,6-tetraacetyl-beta-D-glucopyranosyl-1-O-phenyl)porphin ato]iron (T(o-glu)PPFeCl), chloro[tetra(o-2,3,4,6-tetraacetyl-beta-D-glucop yranosyl-1-O-phenyl)porphinato]manganese (T(o-glu)PPMnCl), chloro[tetra(m-2 ,3,4,6-tetraacetyl-beta-D-glucopyranosyl-1-O-phenyl)porphinato]iron (T(m-gl u)PPFeCl) [tetra(m -2,3,4,6-tetraacetyl-beta-D-glucopyranosyl-1-O-phenyl)po rphinato]manganese T(m-glu)PPMnCl. The newly synthesized compounds were Cha racterized by UV-VIS spectroscopy,(HNMR)-H-1 and elemental analysis. The ca talysis of these acetylglycosylated metalloporphyrins for cyclohexane oxida tion with PhIO as an oxidant at room temperature and under atmospheric pres sure was studied. The changes of the catalytic power of metalloporphyrins w ere observed when acetylglycosyl groups were introduced into porphyrin ring s. In contrast with metalloporphyrins without sugar groups, cyclohexane oxi dation catalyzed by acetylglycosylated metalloporphyrins have higher ratio of cyclohexanol to cyclohexanone as well as reaction rates and yields. The catalytic turnover numbers of acetylglycosylated metalloporphyrins were dou bled compared to metalloporphyrins without sugar groups. The results indica ted that acetylglycosylated metalloporphyrins had better antioxidative stab ility than metalloporphyrins without sugar groups. (C) 2000 Elsevier Scienc e B.V. All rights reserved.