A Multicomponent Coupling Reaction Induced by Insertion of Arynes into the CO Bond of Formamide

4.09 Nucleophilic Coupling with Arynes

“…243 in situ-generated enolates (from malonates or b-diketones) or ketenimine anions (from arylacetonitriles), giving coumarins (98) and 2H-chromenes (99) in high yields (Scheme 84). 245,246 In contrast to the above [2 þ 2] cycloaddition, the reaction of sterically hindered thiones or selones with arynes produces stable four-membered cycloadducts, benzothietes (100), 94,247,248 and benzoselenetes (101) 249 (Scheme 85). However, benzothietes derived from thioureas easily suffer ring-opening to afford product 102 (Scheme 86).…”

Transition-Metal-Free Synthesis of Benzo-Fused Five- and Six-Membered Heterocycles Employing Arynes

“…resulted in the formation of either 2H-chromenes 105 or coumarin derivatives 106 [75,76]. The three-component coupling reaction between aryne, DMF, and an active methylene compound such as acetyl acetone, dibenzoyl methane, cyclohexane 1,3-dione, etc.…”

Highly Efficient Synthesis of New 2H-Chromene Dyes using Cu-SBA-15

“…In the recent years, they have been used in sensors for detection of metals and some compounds with high selectivity 9,10 . Until now, diverse methods have been published for the synthesis of 2H-benzopyran derivatives [11][12][13][14][15][16][17] . They are also good intermediates that have been applied in several organic synthesis [18][19][20] .…”