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In this work, solvent-free microwave irradiation and ultrasonication in an ethanol-water solvent system were presented as viable methods for the synthesis of 2'-hydroxychalcones in a sustainable and facile way via base-catalyzed Claisen-Schmidt condensation from readily available 2'-hydroxyacetophenones and benzaldehydes. Additionally, the synthesis of 3-hydroxyflavone through in-situ oxidative cyclization of a 2'-hydroxychalcone intermediate in a one-pot, two-step approach under ultrasonication is also performed. [ABSTRACT FROM AUTHOR]

Dihydroquinazolinone (DHQZ) has recently been harnessed as a ketone‐derived pro‐aromatic reagent extensively employed in (metalla)photoredox reactions as versatile group transfer agents. In this work, we outline a column chromatography‐free protocol for the multigram‐scale synthesis of pro‐aromatic DHQZs as well as its use in a gram‐scale nickel/photoredox dual‐catalyzed cross‐coupling in single‐batch, photoflow, and simultaneous multiple smaller batches. While the single‐batch approach leveraged moderate yields, a simple plug‐flow photoreactor also exhibited amenable productivity (up to 45 % yield) despite the use of a heterogeneous base. Meanwhile, performing the metallaphotoredox‐catalyzed reaction in multiple smaller batches in an improvised photoreactor facilitated high yields of up to 59 % and good reproducibility, implying a convenient alternative in the absence of photoflow setups. [ABSTRACT FROM AUTHOR]