1,2,3,4-TETRAHYDROISOQUINOLINE

To a solution of the isoquinolinone (1.156 g, 9.90 mmol) and tert-butyl alcohol (0.88 mL, 11.9 mmol) in THF (30 mL) at −78 °C was added liquid ammonia (about 280 mL). Lithium was added in small pieces until the blue coloration persisted, after which the solution was stirred at −78 °C for 30 min. The blue coloration was dissipated with piperlyne, 4-methoxybenzyl chloride (4.83 g, 31.00 mmol) in THF (5 mL) was introduced by syringe, and the mixture was stirred for an additional 150 min at −78 °C. Solid ammonium chloride was added and then the ammonia was allowed to evaporate. The pale yellow residue was partitioned between CH2Cl2 (30 mL) and water (40 mL). The layers were separated, and the aqueous layer was extracted with CH2Cl2 (2 × 30 mL). The combined organic layers were washed with 10% sodium thiosulfate solution (20 mL), dried over magnesium sulfate, and concentrated. Flash chromatography (EtOAc:hexane, 2:1) on silica gave 2.21 g (75%) of the tetrahydroisoquinolinone.  
Reference: Schultz, A. G.; Guzi, T. J.; Larsson, E.; Rahm, R.; Thakker, K. Bidlack, J. M. J. Org. Chem. 1998, 63, 7795–7804.

1, 2, 3, 4-TETRAHYDROISOQUINOLINE belongs to tetrahydroisoquinoline compound, which is encountered in a number of drugs, tubocurarine, one of the quaternary ammonium muscle relaxants^1-3. It is used as a reagent in the preparation of4-(1, 2, 4-oxadiazol-5-yl) piperidine-1-carboxamides as antiproliferative tubulin inhibitors¹. It can be used for the synthesis of 1, 2, 3, 4-tetrahydroisoquinoline-3-carboxylic acid (Tic), which has strong applications in peptides and peptidomimetics design and discovery². 1, 2, 3, 4-tetrahydroisoquinoline has been made into some derivatives with potential for prevention of parkinsonism⁴, cancer treatment5 and acting as Anticonvulsant Agents⁶.

1. https://www.alfa.com/en/catalog/L08143/
2. https://www.ncbi.nlm.nih.gov/pubmed/21235510
3. https://en.wikipedia.org/wiki/Tetrahydroisoquinoline
4. Okuda, K, Y. Kotake, and S. Ohta. "Parkinsonism-preventing activity of 1-methyl-1, 2, 3, 4-tetrahydroisoquinoline derivatives in C57BL mouse in vivo. Biological & Pharmaceutical Bulletin 29.7(2006):1401-1403.
5. Luca, Laura De, et al. "3D Pharmacophore Models for 1, 2, 3, 4‐Tetrahydroisoquinoline Derivatives Acting as Anticonvulsant Agents." Archiv Der Pharmazie 339.7(2006):388-400.
6. Hatano, H, et al. "Tumor-specific cytotoxic activity of 1, 2, 3, 4-tetrahydroisoquinoline derivatives against human oral squamous cell carcinoma cell lines."Anticancer Research 29.8(2009):3079-3086.

clear yellow to brown liquid

1,2,3,4-Tetrahydroisoquinoline is used as a reagent in the preparation of 4-(1,2,4-oxadiazol-5-yl)piperidine-1-carboxamides as antiproliferative tubulin inhibitors.

ChEBI: 1,2,3,4-tetrahydroisoquinoline is a member of isoquinolines.

The Journal of Organic Chemistry, 40, p. 1191, 1975 DOI: 10.1021/jo00897a001
Tetrahedron Letters, 26, p. 4633, 1985 DOI: 10.1016/S0040-4039(00)98771-9