An Addition of Terminal Alkynes to Phthalazin‐2‐Ium Bromide Catalyzed by Copper

Abstract

A copper‐catalyzed addition of alkynes to phthalazin‐2‐ium bromide has been developed under mild conditions, leading to the production of propargylamines analogues. The addition products of a broad scope of phthalazin‐2‐ium bromides bearing various N‐benzyl or alkyl can be obtained in good to high yields. Moderate enantioselectivity was observed in preliminary screening studies of chiral organic ligand.

Transition-Metal-Free Addition of Dialkyl Phosphites to Phthalazin-2-ium Bromide: Synthesis of α-Aminophosphonate Analogues

“…Dioxane was distilled over LiAlH 4 under nitrogen. Phthalazin-2-ium bromide was prepared by a previous procedure . Dialkyl phosphites and other commercially available reagents were purchased from Shanghai Aladdin Biochemical Technology Co. Ltd. and used without further purification.…”

“…Phthalazin-2-ium bromide was prepared by a previous procedure. 28 Dialkyl phosphites and other commercially available reagents were purchased from Shanghai Aladdin Biochemical Technology Co. Ltd. and used without further purification. General Procedure for Addition of Dialkyl Phosphites to Phthalazin-2-ium Bromide.…”

“…Despite these achievements, the reactivity of phthalazin-2-ium is far less explored. In view of the similarity between phthalazin-2-ium and iminium, we have an interest to explore the reactivity of phthalazin-2-ium. , Herein, we would demonstrate a new transition metal-free addition of dialkyl phosphites to phthalazin-2-ium bromide, which presents an efficient approach for synthesis of α-aminophosphonates analogues.…”

“…First, phthalazin-2-ium bromide 1a was examined as the model compound to optimize the reaction condition. Initially, we conceived it might pass through a mechanism involved a carbene insertion and used Cu­(I) as catalyst. , The desired product can be obtained in the presence of 20 mol % of CuI using dioxane as solvent and K 2 CO 3 as base at 110 °C (Table , entry 1). The yield can be further improved when the reaction temperature was reduced to room temperature (Table , entry 2).…”

Chiral Quaternary Ammoniums Derived from Dehydroabietylamine: Synthesis and Application to Alkynylation of Isatin Derivatives Catalyzed by Silver

“…It should be noted that the example of transition metal catalysis on the condition of phase-transfer (chiral cation/ammonium) is very rare [97,98]. Following our interests to the addition of terminal alkyne and utility of chiral natural product [99,100], we had an interest to probe the possibility of quaternary ammonium containing dehydroabietylamine as chiral phase-transfer catalyst. Although the dehydroabietylamine has been broadly used for preparation of quaternary ammonium surfactants, the application of quaternary ammonium bearing dehydroabietylamine as chiral phase-transfer catalyst has been scarcely explored [33][34][35].…”