Intramolecular Catalytic Friedel−Crafts Reactions with Allenyl Cations for the Synthesis of Quinolines and Their Analogues

Abstract

[reaction: see text] This paper describes a novel method to synthesize a quinoline backbone by incorporating allenyl cations into a catalytic intramolecular Friedel-Crafts reaction. The initial products were isomerized and aromatized upon treatment with acid and base, respectively, to give quinolines. The basic concept also proved to be promising for 1-benzazepine, 1-benzazocine, or isoquinoline synthesis.

Innovative Catalytic Protocols for the Ring‐Closing Friedel–Crafts‐Type Alkylation and Alkenylation of Arenes

“…[33] The reaction course involves the formation of highly electrophilic allenyl cations 25 in situ starting from propargyl silyl ethers 24. These intermediates smoothly undergo cyclization to form tetrahydroquinolines in good yields (higher than 90 %) and high regioselectivity.…”

Intramolecular Alkynylcyclopropanation of Olefins Catalyzed by Bi(OTf)3: Stereoselective Synthesis of 1‐Alkynyl‐3‐azabicyclo[3.1.0]hexanes

“…Thus, the overall mechanism is considered to be a formal addition reaction of propargyl carbene A to the olefin. However, the allene intermediate B is often supplemented with other unexpected nucleophiles,13 spontaneously eliminates substituents,12a, 14 or sometimes oligomerizes. Indeed, when the model substrate N ‐tosyl‐5‐azaoct‐7‐en‐2‐yn‐1‐ol ( 1 a ) was treated with various Lewis acids (5 mol %), such as BF 3 ⋅ OEt 2 , Sc(OTf) 3 , Cu(OTf) 2 , PtCl 2 , AgOTf, or TfOH, at 80 °C in 1,2‐dichloroethane (DCE), only oligomeric products were formed [Eq.…”

Efficient Manganese/Copper Bimetallic Catalyst for N‐Arylation of Amides and Sulfonamides Under Mild Conditions in Water

“…1 [23] Following the general procedure, 3 [24] Following the general procedure, 3-fluorobenzamide (205 mg, 1.47 mmol) and [24,25] [22] Following the general procedure, 4 [26] Following the general procedure, 4-methylbenzamide (198 mg, 1.47 mmol) and [27] [19] Following the general procedure, 4 N-(4-Chlorophenyl)-4-methoxybenzamide (7b): [28] Following the general procedure, 4-methoxybenzamide (222 mg, 1.47 mmol) and [28] [20] Following the general procedure, 4 [29] Following the general procedure, 4-chlorobenzamide (222 mg, 1.47 mmol) and [28] [30][31][32] Following the general procedure, p-toluenesulfonamide (0. [34] Following the general procedure, p-toluenesulfonamide (0.252 g, 1.47 mmol) and 3-chloroiodobenzene (0.273 mL, 2.21 mmol) provided the coupled product. Purification of the crude oil by flash chromatography (hexane/ethyl acetate, 85:15) gave 10b (133 mg, 33 % yield) as a yellowish solid.…”