261729-99-1Relevant articles and documents
Super acid-induced pummerer-type cyclization reaction: Improvement in the synthesis of chiral 1,3-dimethyl-1,2,3,4-tetrahydroisoquinolines
Saitoh, Toshiaki,Shikiya, Kentaro,Horiguchi, Yoshie,Sano, Takehiro
, p. 667 - 672 (2007/10/03)
Improved synthesis of four stereoisomeric chiral 1,3-dimethyl-1,2,3,4- tetrahydroisoquinolines (1a, b, ent-1a, b) was achieved via the super acid-induced cyclization of chiral N-[1-methyl-2-(phenylsulfinyl)ethyl]-N-(1- phenylethyl)formamides (4a, b, ent-4a, b) using the Pummerer-type cyclization reaction as a key step. The cyclization leading to the isoquinoline ring proceeded in a quantitative manner when trifluoromethane sulfonic acid (TFSA) was used as the super acid, although Friedel-Crafts-type alkylation of 4-phenylsulfanyl TIQ derivatives (5) with benzene used as the solvent accompanied cyclization to yield the 4-phenyl-TIQs (7). The byproduct (7) was exclusively formed when a large excess amount of TFSA was used.
A Chiral Synthesis of Four Stereoisomers of 1,3-Dimethyl-1,2,3,4-tetrahydroisoquinoline, an Inducer of Parkinson-like Syndrome
Toda, Jun,Matsumoto, Shinobu,Saitoh, Toshiaki,Sano, Takehiro
, p. 91 - 98 (2007/10/03)
Four stereoisomers of 1,3-dimethyl-1,2,3,4-tetrahydroisoquinoline, an inducer of Parkinson-like syndrome, were synthesized by applying a new method of 1,2,3,4-tetrahydroisoquinoline (TIQ) synthesis utilizing the Pummerer reaction as a key step. The chiral centers at C-1 and C-3 were constructed by two routes starting from alaninol (3) and 1-phenylethylamine (4) as a chiral source. Enantiomerically pure 1,3-dimethyl-TIQs (1R,3S)-(1), (1S,3R)-(ent-1), (1S,3S)-(2), and (1R,3R)-(ent-2) were prepared in a stereochemically unambiguous manner from 3 in 11 steps (route I) and from 4 in 6 steps (route II). The conformations of tetrahydroisoquinoline ring in 1-methyl, 3-methyl, and 1,3-dimethyl-TIQs were discussed on the basis of their CD, 1H-NMR spectra, and steric energies.