Methods for the synthesis of amines such as ephedrine and intermediates

摘要

A method for the preparation of a compound of formula (VI): in which R₂ is an optionally substituted C1–C6 alkyl; R₄ is H, OH, an optionally substituted C1–C6 alkyl or an optionally substituted C1–C6 alkoxy; R₅ is an optionally substituted aryl, an optionally substituted aralkyl, or an optionally substituted alkyl; and R₆ is H or an optionally substituted C1–C6 alkyl; the method including the step of subjecting a ketone of formula (V) in which R₂, R₄ and R₅ are as defined above, to reductive amination with an amine of formula R₃NH₂ in which R₃ is an optionally substituted alkyl, and a reductant to form the compound of formula (VI), wherein the reaction is conducted in the presence of a supercritical fluid or a liquefied gas.