Nf. Yu et al., A one-pot synthesis of tetrahydroisoquinolonic acids from aldehydes and amines in trimethylorthoformate, SYNLETT, (3), 2000, pp. 355-356
Tetrahydroisoquinolonic acids are synthesized in the presence of excess tri
methyl orthoformate by a one-pot procedure directly from the corresponding
amines, aldehydes and homophthalic anhydride.