Co(salen)-Catalyzed tert-Butyl Hydroperoxide Oxidation of tert-Butylphenols Bearing an Unsaturated Side Chain
摘要:
Co(salen)-catalyzed oxidation of 2,4- and 2,6-di-tert-butylphenols bearing an unsaturated side chain, with tert-butyl hydroperoxide (TBHP) in CH2Cl2 at rt, results predominantly in the formation of tert-butylperoxylated products. The position of tert-butylperoxylation depends on the nature of the unsaturated side chain: predominantly the ortho position for 4-alkynyl-2,6-di-tert-butylphenols, the side chain for 4-alkenyl-2,6-di-tert-butylphenols, and the para position for 4-cyano- or 4-(1-methoxyimino)alkyl-2,6-di-tert-butylphenols as well as 2-alkynyl-, 2-alkenyl-, and 2-cyano-4,6-di-tert-butylphenols. The ortho tert-butylperoxylated products arise mainly from initially formed para tert-butylperoxylated products, by migration of the tert-butylperoxy group.
Co(salen)-Catalyzed tert-Butyl Hydroperoxide Oxidation of tert-Butylphenols Bearing an Unsaturated Side Chain
摘要:
Co(salen)-catalyzed oxidation of 2,4- and 2,6-di-tert-butylphenols bearing an unsaturated side chain, with tert-butyl hydroperoxide (TBHP) in CH2Cl2 at rt, results predominantly in the formation of tert-butylperoxylated products. The position of tert-butylperoxylation depends on the nature of the unsaturated side chain: predominantly the ortho position for 4-alkynyl-2,6-di-tert-butylphenols, the side chain for 4-alkenyl-2,6-di-tert-butylphenols, and the para position for 4-cyano- or 4-(1-methoxyimino)alkyl-2,6-di-tert-butylphenols as well as 2-alkynyl-, 2-alkenyl-, and 2-cyano-4,6-di-tert-butylphenols. The ortho tert-butylperoxylated products arise mainly from initially formed para tert-butylperoxylated products, by migration of the tert-butylperoxy group.
A copper-catalyzed annulative amination approach to 3-aminobenzofurans and -indoles from o-alkynylphenols and -anilines has been developed. The Cu-based catalysis is based on an umpolung, electrophilic amination with O-benzoyl hydroxylamines and enables the mild and convergent synthesis of various 3-aminobenzoheteroles of biological and pharmaceutical interest. Some mechanistic investigations and an application of this protocol to construction of more complex tricyclic framework are also described.
Copper-Catalyzed Annulative Amination of <i>ortho</i>-Alkynylphenols with Hydroxylamines: Synthesis of 3-Aminobenzofurans by Umpolung Amination Strategy
作者:Koji Hirano、Tetsuya Satoh、Masahiro Miura
DOI:10.1021/ol200651r
日期:2011.5.6
A room temperature copper-catalyzed annulative amination of ortho-alkynylphenols with electrophilic amination reagents, O-acylated hydroxylamines, proceeds efficiently to provide the corresponding 3-aminobenzofurans of biological and pharmaceutical interest.