952516-34-6

2-Amino-4H-chromenes were synthesized in moderate to good yields by the reaction of o-quinone methides photochemically generated from o-(dimethylaminomethyl)phenols with malononitrile. This method was applicable to the synthesis of fluorinated chromenes that were difficult to obtain by other methods. In addition, o-(hydroxymethyl)phenols could be used for the reaction in the presence of tertiary amine bases.

Initiated by CCl3Br, phenols undergo efficient ortho-selective oxidative cross dehydrogenative coupling (CDC) with trimethylamine. When tetramethylethylenediamine (TMEDA) is used instead of trimethylamine, oxidative carbon-carbon activation coupling (CAC) could occur to give the same salicylamines together with CDC by-products. These reactions are accelerated by a gold salt.

Phenols were converted to their magnesium salts with the MgCl2-Et3N base system and subsequently reacted with Eschenmoser's salt, affording N,N-dimethyl substituted benzylamines in high to excellent yields. A series of mono N-substituted benzylamines were prepared in one-pot syntheses by ortho-formylation of phenols to corresponding salicylaldehydes, which in turn reacted with amines to imines. The imines were subsequently reduced to mono N-substituted benzylamines. Some of these benzylamines were further converted, without work-up, to mono N-substituted dihydro-2H-1,3-benzoxazines.