Greener [3+3] tandem annulation–oxidation approach towards the synthesis of substituted pyrimidines

Abstract

An efficient and practical method using choline hydroxide has been developed for the production of a wide range of substituted pyrimidines.

Optimizing Optoelectronic Properties of Pyrimidine‐Based TADF Emitters by Changing the Substituent for Organic Light‐Emitting Diodes with External Quantum Efficiency Close to 25 % and Slow Efficiency Roll‐Off

“…The synthetic route and chemical structures of 4,6‐bis(4‐(10 H ‐phenoxazin‐10‐yl)phenyl)pyrimidine ( PXZPM ), 4,6‐bis(4‐(10 H ‐phenoxazin‐10‐yl)phenyl)‐2‐methylpyrimidine ( PXZMePM ), and 4,6‐bis(4‐(10 H ‐phenoxazin‐10‐yl)phenyl)‐2‐phenylpyrimidine ( PXZPhPM ) are outlined in Scheme . The key intermediates, PM‐2Br , MePM‐2Br , and PhPM‐2Br , were simply synthesized according to the previously reported procedures . The Pd‐catalyzed C−N cross‐coupling of RPM‐2Br and 10 H ‐phenoxazine affords the target compounds, PXZPM , PXZMePM , and PXZPhPM , in high yields of over 90 %.…”

“…The key intermediates, PM-2Br, MePM-2Br,a nd PhPM-2Br,w ere simplys ynthesized according to the previously reportedp rocedures. [16] TheP d-catalyzed CÀNc ross-coupling of RPM-2Br and 10H-phenoxazine affords the target compounds, PXZPM, PXZMePM,a nd PXZPhPM,i nh igh yields of over 90 %. All of the final products were purifiedb yr ecrystallization from am ixture of dichloromethane/n-hexane and further gradient sublimation.…”

“…Precursors, 4,6-bis(4-bromophenyl)pyrimidine (PM-2 Br), 4,6-bis(4bromophenyl)-2-methylpyrimidine (MePM-2Br), and 4,6-bis(4-bromophenyl)-2-phenylpyrimidine (PhPM-2Br)w ere synthesized according to the literature. [16] Standard procedures are used to dry the solvents. Unless otherwise stated, all reagents were used as received without further purification.…”

Acid‐Catalyzed Pseudo Five‐Component Annulation for a General One‐Pot Synthesis of 2,4,6‐Triaryl Pyrimidines

“…2,4,6‐Trisubstituted pyrimidines have been synthesized by various routes including the reactions of amidines with α,β‐unsaturated ketones, with benzaldehydes and ketones, and with up to three different alcohols catalyzed by Mn/Ir/Pt (Scheme , eq 1) –. They were also prepared by the condensation of 1,3‐diketones with aldehydes and NH 4 OAc, by reaction of alkynes and nitriles in the presence of Lewis acids, and by microwave‐assisted four‐component reaction between ketones, benzaldehydes, nitriles and hydroxylamine (Scheme , eq 2)., Alternatively, annulation of ketones with two molecules of nitriles (Scheme , eq 3), or cyclization of aldehydes, N‐benzyl amidines and DMSO promoted by base, or arylation of halogenated pyrimidines via Suzuki coupling has also been reported .…”

Metal‐Free Synthesis of Coumarin‐fused Pyrimidines from 4‐Aminocoumarins via Pseudo Four‐component Reaction

“…For instance, Trimarco et al reported a two‐step method for the synthesis of chromeno[4,3‐ d ]pyrimidin‐5‐ones from 4‐azidocoumarins and enamines via intermediate amidines (Scheme , a). Chaskar and co‐workers presented one example involving chromeno[4,3‐ d ]pyrimidin‐5‐one through choline hydroxide‐promoted cyclization of 3‐acetyl coumarin with benzamidine hydrochloride followed by aerobic oxidation under air (Scheme , b). Gaddamanugu's group developed a protocol for ready access to 5‐oxo‐chromeno[4,3‐ d ]pyrimidine 3‐oxides from 4‐chloro‐3‐formylcoumarin and aromatic carboxamide oximes via tandem base‐mediated annulation/dehydration reaction (Scheme , c).…”