Concise Synthesis of 1,2-Dihydroisoquinolines and 1H-Isochromenes by Carbophilic Lewis Acid-Catalyzed Tandem Nucleophilic Addition and Cyclization of 2-(1-Alkynyl)arylaldimines and 2-(1-Alkynyl)arylaldehydes

Abstract

By using carbophilic Lewis acids, In(OTf)3, NiCl2, and AuCl(PPh3)/AgNTf2, a concise and efficient synthesis of 1,3-disubstituted 1,2-dihydroisoquinolines has been achieved via tandem nucleophilic addition and cyclization of 2-(1-alkynyl)arylaldimines. Addition of proton sources such as water, CF3CH2OH, and 2,6-di-tert-butyl-4-methoxyphenol was essential for the Lewis acid-catalyzed tandem reactions with organometallic reagents. By switching these catalysts, various types of nucleophiles such as allylstannanes, silyl enol ethers, alkenylboronic acids, and active methylene compounds could be introduced at the C1 position of 1,2-dihydroisoquinolines in this transformation. Furthermore, this method proved to be applicable to the synthesis of 1H-isochromene derivatives via the same tandem reaction of 2-(1-alkynyl)arylaldehydes.

Facile Synthesis of 4‐(Trifluoromethyl)‐1 H‐isochromenes from Alkynols

“…2016, 5,2 40 -245 www.AsianJOC.org 69. 7, 55.5, 55.3 9,158.2,145.7,131.0,129.9,129.3,128.0,125.0 (q,J = 269.4 Hz),123.9,121.3,113.7,110.0,69.7,55.5,35.9,31.5,30.9,22.5,14.0 5,159.1,159.0,137.0,131.7,129.1,127.6,126.1,126.0,125.1 (q,J = 269.3 Hz),124.8,123.8,122.4,122.3,113.4,69.8,55.3,21 + :308.0824; found:308.0826. 161.7,132.5,131.9,131.8,129.0,128.7,127.6,125.6,125.5,125.4,125.1,124.8 (q,J = 269.3 Hz),122.7,122.6,121.2,121.1,113.5,104.5 9, 160.8, 134.5,...…”

“…[4,5] This is considered ap art of hydrofunctionalization. [4] Metal-catalyzed alkynol cyclization offers ar eliable and atom-economic methodo fo btaining highly functionalized, oxygen-containing heterocycles, [6] but this cyclization approachoften leads to protonation products withoutfurther derivatization.…”

PtII‐Catalyzed Synthesis of 9‐Oxabicyclo[3.3.1]nona‐2,6‐dienes from 2‐Alkynyl‐1‐carbonylbenzenes and Allylsilanes by an Allylation/Annulation Cascade

“…[2] New [3+2] and [4+2] annulations were reported for aldehyde substrates bearing an a-or b-siloxy group, [3] but these annulations required 1.0-5.0 equivalents of a Lewis acid (BF 3 ·Et 2 O, TiCl 4 , or SnCl 4 ). [2][3][4] Our objective was to explore new annulations of allysilanes with functionalized aldehydes by using soft-acid-metal species in catalytic proportions.…”

“…[2] New [3+2] and [4+2] annulations were reported for aldehyde substrates bearing an a-or b-siloxy group, [3] but these annulations required 1.0-5.0 equivalents of a Lewis acid (BF 3 ·Et 2 O, TiCl 4 , or SnCl 4 ). [2][3][4] Our objective was to explore new annulations of allysilanes with functionalized aldehydes by using soft-acid-metal species in catalytic proportions. [4,5] Herein, we report a one-pot Pt II -catalyzed synthesis of 9-oxabicyclo[3.3.1]nona-2,6-dienes by a tandem allylation/annulation reaction of the oxo-alkyne functionalities with 2-substituted allylsilanes (see Table 1).…”

“…[2][3][4] Our objective was to explore new annulations of allysilanes with functionalized aldehydes by using soft-acid-metal species in catalytic proportions. [4,5] Herein, we report a one-pot Pt II -catalyzed synthesis of 9-oxabicyclo[3.3.1]nona-2,6-dienes by a tandem allylation/annulation reaction of the oxo-alkyne functionalities with 2-substituted allylsilanes (see Table 1). The importance of this new synthesis is that it provides easy access to two classes of bioactive molecules, I-IV and V, which are comprised of the oxatricyclic framework that showed biological effects in the central nervous system, [6] as well as HIV-1 inhibitory activities [7] ( Figure 1).…”