Direct access to 2-(N-alkylamino)pyrimidines via ruthenium catalyzed tandem multicomponent annulation/N-alkylation

2-(N-alkylamino)pyrimidines are important heterocycles widely found in various pharmaceutically important drugs. Here, we have disclosed a new cooperative ruthenium complex catalyzed tandem mul-ticomponent synthesis of 2-(N-alkylamino)pyrimidines directly from guanidine salt and alcohols. The reactions proceeded through the dehydrogenation of alcohols, followed by C-C coupling and sequential C-N coupling with guanidine and primary alcohol, with the elimination of three equivalents of hydrogen gas. In this work, application of both the acceptorless dehydrogenative coupling (ADC) and borrowing hydrogen (BH) strategies were accomplished in a single reaction. This catalytic method tolerated a wide range of substrates. The viability of the current method was demonstrated by preparative scale synthesis of a few products. A plausible catalytic cycle was proposed based on various control experiments, mech-anistic studies and DFT calculations. Remarkably, 42 new 2-(N-alkylamino)pyrimidines were synthesized following this catalytic protocol. (c) 2021 Elsevier Inc. All rights reserved.

Automated summary

A new cooperative ruthenium complex catalyzed method was developed for the multicomponent synthesis of 2-(N-alkylamino)pyrimidines, demonstrating tolerance to a wide range of substrates and successful preparative scale synthesis of several products.