Synthesis of trans 8-substituted-6-phenyl-6, 7, 8, 9-tetrahydro-3H-pyrazolo [4, 3-f]isoquinolines using a Pictet-Spengler approach. Issue 51 (19th December 2018)

• Record Type: Journal Article
• Authors: Bailey, Andrew; Lister, Andrew; Moss, Thomas; Scott, James S.; Wu, Ye; Lamont, Scott G.
• Is Part Of: Tetrahedron letters. Volume 59:Issue 51(2018)
• Page Start: 4509
• Page End: 4513
• Publication Date: 2018-12-19
• Subjects: 6, 7, 8, 9-Tetrahydro-3H-pyrazolo[4, 3-f]isoquinoline -- Pictet-spengler -- Stereocontrol; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2018.11.021
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: Pictet-Spengler used to construct a tricyclic indazole core. Synthetic routes developed to enable efficient generation of indazole precursors. Trans stereochemistry generated. Abstract: In the following communication we report two complementary approaches for the synthesis of trans 8-substituted-6-phenyl-6, 7, 8, 9-tetrahydro-3 H -pyrazolo[4, 3- f ]isoquinolines. The first method, directly from α-methyl substituted indazole ethanamines, was successful but had limited substrate scope. The second method utilised a modified Pictet-Spengler cyclisation reaction on an aniline substrate followed by late stage construction of the indazole ring and was more versatile in terms of substrate scope.