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Tertiary amines are ubiquitous and valuable compounds in synthetic chemistry, with a wide range of applications in organocatalysis, organometallic complexes, biological processes and pharmaceutical chemistry. One of the most frequently used pathways to synthesize tertiary amines is the reductive amination reaction of carbonyl compounds. Despite developments of numerous new reductive amination methods in the past decades, this reaction generally requires non-atom-economic processes with harsh conditions and toxic transition-metal catalysts. Herein we report simple yet practical protocols using triflic acid as catalyst to efficiently promote direct reductive amination reactions of carbonyl compounds on a broad ranges of substrates. Applications of this new method to generate valuable heterocyclic frameworks and polyamines are also included.