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L‐Amino acids (L‐Ala, L‐Phe, L‐Val, L‐Pro) were used as a source of chirality in the diastereoselective synthesis of tetrahydroisoquinoline derivatives. The key step was the Pictet−Spengler condensation of ketoamides 4 and 10, which proceeded under very mild conditions. L‐Ala, L‐Phe and L‐Val gave rise the R‐configuration at the newly formed stereogenic center. Surprisingly, L‐Pro gave the opposite result. The stereochemistry of 6d and 12a were established on the basis of X‐ray crystallographic data. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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L-(−)-Phenylalanine, L-(+)-valine, and L-(−)-proline were used in the diastereoselective synthesis of benzyltetrahydroisoquinoline derivatives.The search for methods for the asymmetric synthesis of chiral compounds has been an area of intense study over the past two decades. 1 The need for the preparation of chiral compounds in enantiomerically pure form has increased lately as a result of several factors, mainly connected with a stereodiscrimination of chiral compounds by most biological systems and therefore the pressure on the pharmaceutical industry to develop nonracemic drugs. Tetrahydroisoquinolines still attract considerable interest in the modern chemistry of biologically active compounds, and consequently several new effective approaches for their stereocontrolled synthesis have recently been developed. 2 Special attention has been devoted to the asymmetric synthesis using enantiospecific processes proceeding from the chiral pool to gain access to this broad class of compounds. 3 Of all the members of chiral