2-Amino-4-methylphenol, synthesis

Amino-4-methylphenol, synthesis of spirobis[l,3,2-benzoxaza-phosphole], 163... 

Chida et al. reported the first total synthesis of murrastifoline-A (186) starting from 2-amino-5-methylphenol (1062) (666,667). This synthesis involves a palladium(O)-catalyzed double N-arylation of the arylamine (1082) with 2,2 -dibromobiphenyl 1075 as a key step. 

In 1997, the first truly catalytic enantioselective Mannich reactions of imines with silicon enolates using a novel zirconium catalyst was reported [9, 10]. To solve the above problems, various metal salts were first screened in achiral reactions of imines with silylated nucleophiles, and then, a chiral Lewis acid based on Zr(IV) was designed. On the other hand, as for the problem of the conformation of the imine-Lewis acid complex, utilization of a bidentate chelation was planned imines prepared from 2-aminophenol were used [(Eq. (1)]. This moiety was readily removed after reactions under oxidative conditions. Imines derived from heterocyclic aldehydes worked well in this reaction, and good to high yields and enantiomeric excesses were attained. As for aliphatic aldehydes, similarly high levels of enantiomeric excesses were also obtained by using the imines prepared from the aldehydes and 2-amino-3-methylphenol. The present Mannich reactions were applied to the synthesis of chiral (3-amino alcohols from a-alkoxy enolates and imines [11], and anti-cc-methyl-p-amino acid derivatives from propionate enolates and imines [12] via diastereo- and enantioselective processes [(Eq. (2)]. Moreover, this catalyst system can be utilized in Mannich reactions using hydrazone derivatives [13] [(Eq. (3)] as well as the aza-Diels-Alder reaction [14-16], Strecker reaction [17-19], allylation of imines [20], etc. 

The oxidation of substituted o-diphenols to the corresponding o-benzoquinones in the presence of 4 different binuclear copper complexes has been investigated by Bolus and Vigee [14]. The initial rates of oxidation were within a factor of 4 for the substrates catechol, 4-methylcatechol, dopamine, 3,4-dihydroxybenzoic acid, and 3,4-dihydroxybenzonitrile. The ligands of the catalyst complexes were Schiff-base type derivatives of 2,6-diformyI-4-methylphenol with diamines and amino acids their synthesis and characterization have been reported [15]. 

Synthesis of 2,6-bis(((2-methoxyethyl) (pyridin-2-ylmethyl)amino ) methyl)-4-methylphenol (CH3HL2)... 

---