A modified Bischler-Napieralski procedure for the synthesis of 3-aryl-3,4-dihydroisoquinolines
摘要:
A modification of the Bischler-Napieralski reaction for the cyclization of (1,2-diphenylethyl)amides to the 3-aryl-3,4-dihydroisoquinolines is presented. Elimination of the amide group as the nitrile via the retro-Ritter reaction is avoided by its conversion to an N-acyliminium intermediate with oxalyl chloride-FeCl3. Removal of the oxalyl group in refluxing MeOH-sulfuric acid provides the 3,4-dihydroisoquinolines in moderate to high yields. The method is also highly effective with (2-phenylethyl)amides.
Use of the<i>N</i>-Formyliminium Ion Cyclization for the Synthesis of 3-Aryl-1,2,3,4-tetrahydroisoquinolines
作者:Bruce E. Maryanoff、Mary C. Rebarchak
DOI:10.1055/s-1992-26350
日期:——
Classical cyclization procedures for the synthesis of 3-arylisoquinolines are fraught with complications. Here, we present the application of an N-acyliminium cyclization to such target molecules. N-(1,2-diarylethyl)formamides 1, 4a-4d, and 4f were cyclized to the respective tetrahydroisoquinolines by using paraformaldehyde under mildly acidic conditions. Yields ranged from good to excellent. Cyclization of 4e was unsuccessful possibly because the presence of the 4-methoxyphenyl group leads to ionization of the formamido group.
A modified Bischler-Napieralski procedure for the synthesis of 3-aryl-3,4-dihydroisoquinolines
作者:Robert D. Larsen、Robert A. Reamer、Edward G. Corley、Paul Davis、Edward J. J. Grabowski、Paul J. Reider、Ichiro Shinkai
DOI:10.1021/jo00021a014
日期:1991.10
A modification of the Bischler-Napieralski reaction for the cyclization of (1,2-diphenylethyl)amides to the 3-aryl-3,4-dihydroisoquinolines is presented. Elimination of the amide group as the nitrile via the retro-Ritter reaction is avoided by its conversion to an N-acyliminium intermediate with oxalyl chloride-FeCl3. Removal of the oxalyl group in refluxing MeOH-sulfuric acid provides the 3,4-dihydroisoquinolines in moderate to high yields. The method is also highly effective with (2-phenylethyl)amides.
Regioselective Lithiation and Electrophilic Quenching of
<i>N</i>
‐Boc‐3‐phenyltetrahydroisoquinoline
作者:Ruaa A. Talk、Ashraf El‐Tunsi、Craig C. Robertson、Iain Coldham
DOI:10.1002/ejoc.201900238
日期:2019.9
1‐substituted derivatives is to carry out the lithiation at C‐1 followed by trapping with an electrophile. Here we explore the feasibility of lithiation at C‐3 by using a substrate with a benzylic proton on both sides of the nitrogen atom such that lithiation with nBuLi could occur at either C‐1 or C‐3 of the tetrahydroisoquinoline. The regioselectivity in the lithiation was determined using the substrate N