Synthesis of glycoconjugated metalloporphyrins and their selective catalysis for alkane oxidation under mild conditions

Two glycoconjugated porphines, tetra[2-acetylglucosyl-oxo-phenyl]porphine [T(o-glu)PPH2] and tetra[3-acetylglycosy-oxo-phenyl]porphine[T(m-glu)PPH2], were synthesized from the reaction of pyrrole with ortho-acetylglycosylate benzaldehyde and meta- acetylglycosylate benzaldehyde, respectively, by using Lindsey' s method. Four glycoconjugated metalloporphyrins, chloro [tetra(o-2, 3,4, 6-O-acetylglucose-1-O-phenyl) porphinato] iron [T(o-glu)PPFeCl], chloro[tetra(o-2, 3, 4, 6-O-acetylglucose-1-O-phenyl) porphinato] manganese, [T(o-glu) PPMnCl], chloro [tetra(m-2, 3, 4, 6-O-acetylglucose-1-O-phenyl) porphinato] iron [T(m-glu) PPFeCl] and chloro[tetra(m-2, 3,4, 6-O-acetylglucose-1-O-phenyl) porphinato] manganese [T(m-glu)PPMnCl] were prepared from these glycoconjugated porphines. The newly synthesized compounds were characterized by UV-vis spectroscopy, elemental analysis and H-1 NMR. The catalytic oxidation of 2-methylbutane with PhIO as an oxidant at room temperature and under atmospheric pressure by four glycoconjugated metalloporphyrins was studied, The research showed that glycoconjugated metalloporphyrins catalyzed regiospecifically the hydroxylation of the primary carbon-hydrogen bonds of 2-methylbutane, and that non-glycoconjugated metalloporphyrins catalyzed selectively the oxidation of secondary and tertiary carbon-hydrogen bonds of 2-methylbutane. In contrast with metalloporphyrins without sugar groups, the selective catalysis of these glycoconjugated metalloporphyrins for hydrocarbon oxidation was closer to cytochrome P-450 monooxygenase.