Titanium-Catalyzed Selective N-Alkylation of Amines with Alcohols via Borrowing Hydrogen Methodology

Polynaphthoquinone mediated metal-free direct N-alkylation of (hetero)aryl amines using alcohols

Herein, we present polynaphthoquinone as an effective metal-free catalyst for the direct N-alkylation of aryl and heteroaryl amines using alcohols. Our experiments reveal that the optimal reaction conditions consist of 1.0 mmol of alcohol, 1.5 mmol of aniline, 0.8 equivalents of t-BuOK, and 30 wt% polynaphthoquinone catalyst in toluene at 135 °C under an inert atmosphere for 24 hours. Control experiments confirm that without a catalyst or base, the reaction fails to progress. Additionally, the reused catalyst in subsequent reactions yields good to excellent results. This methodology has also been extended to the dehydrogenative synthesis of quinolines and indoles.

Au(III)/TPPMS-catalyzed Friedel-Crafts benzylation of deactivated N-alkylanilines in water

The Friedel-Crafts reaction of electronically deactivated anilines including those with strong electron-withdrawing NO2, CN or CO2H groups is challenging due to the reduced electron density of the aromatic ring. Here, we demonstrate the Au(III)/TPPMS-catalyzed Friedel-Crafts benzylation of deactivated anilines in water. This reaction exhibits operational simplicity and a broad substrate scope with high regioselectivity, enabling rapid access to 2-benzylanilines.

Preparation of a novel cadmium-containing coordination polymer and catalytic application in the synthesis of N-alkylated aminoquinoline derivatives via the borrowing hydrogen approach

Herein, we report an efficient and straightforward approach for the synthesis of N-alkylated aminoquinoline derivatives by recyclable Cd-containing coordination polymer-catalyzed reactions of aminoquinolines with primary alcohols via the borrowing hydrogen strategy. In this work, a new type of coordination polymer [Cd(CIA)(phen)2(H2O)]n was successfully designed and fabricated. The molecular structure was corroborated by single-crystal X-ray diffraction and fully characterized by PXRD, FT-IR, TGA, and XPS. Importantly, this polymer revealed high catalytic activity for the N-alkylation reaction of 2-aminoquinoline and 8-aminoquinoline with inexpensive and low-toxicity alcohols as alkylating agents in excellent yields up to 95%. Interestingly, the present synthetic protocol was successfully applied for the gram-level synthesis of several biologically active compounds. In addition, several control reactions were carried out to investigate the possible mechanisms of this transformation. Finally, recycling experiments indicated that the cadmium coordination polymer showed good recovery performance for borrowing hydrogen reactions.