Glycoporphyrin Catalysts for Efficient C–H Bond Aminations by Organic Azides
摘要:
We report herein the synthesis of new glycoporphyrin ligands which bear a glucopyranoside derivative on each meso-aryl moiety of the porphyrin skeleton. The saccharide unit is directly conjugated to the porphyrin or a triazole spacer is placed between the carbohydrate and porphyrin ring. The obtained glycoporphyrin ligands were employed to synthesize cobalt(II), ruthenium(II), and iron(III) complexes which were tested as catalysts of C-H bond aminations by organic azides. Two of the synthesized complexes were very efficient in promoting catalytic reactions, and the results achieved indicated that ruthenium and iron complexes show an interesting complementary catalytic activity in several amination reactions. The eco-friendly iron catalyst displayed very good chemical stability in catalyzing the amination reaction for three consecutive runs without losing catalytic activity.
Co(porphyrin) complexes promote an unusual reactivity of dihydronaphthalene towards several aryl azides. The reaction affords the benzylic amine of tetrahydronaphthalene instead yielding the amine of dihydronaphthalene as it normally happens in the presence of Ru(porphyrin)CO catalysts. The amination process occurs with the concomitant reduction of the dihydronaphthalene double bond probably due to the high reactivity of the endocyclic C=C bond coupled with the good hydrogen donor capability of dihydronaphthalene. Two mechanisms for this reaction are proposed. (C) 2012 Elsevier B. V. All rights reserved.
Glycoporphyrin Catalysts for Efficient C–H Bond Aminations by Organic Azides
We report herein the synthesis of new glycoporphyrin ligands which bear a glucopyranoside derivative on each meso-aryl moiety of the porphyrin skeleton. The saccharide unit is directly conjugated to the porphyrin or a triazole spacer is placed between the carbohydrate and porphyrin ring. The obtained glycoporphyrin ligands were employed to synthesize cobalt(II), ruthenium(II), and iron(III) complexes which were tested as catalysts of C-H bond aminations by organic azides. Two of the synthesized complexes were very efficient in promoting catalytic reactions, and the results achieved indicated that ruthenium and iron complexes show an interesting complementary catalytic activity in several amination reactions. The eco-friendly iron catalyst displayed very good chemical stability in catalyzing the amination reaction for three consecutive runs without losing catalytic activity.