Visible-light induced cascade radical cyclization of sulfinic acids and o-(allyloxy)arylaldehydes towards functionalized chroman-4-ones

Copper-Catalyzed Difluoroalkylation Reaction

“…In the past few years, great progress on photocatalysis has been made in the field of organic chemistry [ 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 ] since the pioneer works carried out by MacMillan et al [ 74 ] and Yoon et al [ 75 ] in 2008. In the presence of visible light, a difluoroalkylation reaction could proceed smoothly using RCF 2 X as an important synthon.…”

Recent advances in free radical cyclizations of 2-alkenyl benzaldehydes to synthesize benzocycloketones

“…In the same year, Wang's group has also developed an efficient and one-pot approach to synthesize sulfone-functionalized chroman-4-ones 99 by using Na 2 -Eosin Y as the photocatalyst, K 2 S 2 O 8 as the oxidant via the visible light-induced radical sulfonylation and difunctionalization of 2-alkenylbenzaldehydes 1 with arylsulfinic acids 104 (Scheme 23). 40 The authors believe that the sulfonylation transformation is achieved through the mechanism of free radical coupling.…”

Metal-Free Synthesis of Carbamoylated Chroman-4-Ones via Cascade Radical Annulation of 2-(Allyloxy)arylaldehydes with Oxamic Acids

“…However, these methods often encounter some shortcomings, such as harsh reaction conditions, multi-step production and limited substrate scopes. Recently, the cascade radical annulation of 2-(allyloxy)arylaldehydes triggered by diverse radicals, including alkyl [ 14 , 15 , 16 , 17 , 18 , 19 ], acyl [ 20 , 21 ], trifluoromethyl [ 22 , 23 ], phosphoryl [ 22 , 23 , 24 , 25 ], and sulfonyl radicals [ 26 , 27 , 28 ] has been emerging as an atom- and step-economical approach for the construction of various functionalized chroman-4-ones. Among these methodologies, decarboxylative radical annulation of 2-(allyloxy)arylaldehydes using different types of carboxylic acids as radical precursors has made great achievements.…”