Ultrasound-assisted synthesis of RO- and RS-substituted (hetero)acenes via oxo- and thio-Friedel-Crafts/Bradsher reactions

O,S-Acetals in a New Modification of oxo-Friedel–Crafts–Bradsher Cyclization—Synthesis of Fluorescent (Hetero)acenes and Mechanistic Considerations

“…5,7,8,9-Tetramethoxyanthra[2,3-d][1,3]dioxole 7a [ 34 ]. 1 H NMR (200 MHz, C 6 D 6 ): 8.52 (s, 1H), 7.74 (s, 1H), 7.37 (s, 1H), 7.20 (s, 1H), 5.35 (s, 2H), 4.01 (s, 3H), 3.93 (s, 3H), 3.81 (s, 3H), 3.56 (s, 3H) ppm.…”

“…5,7-Dimethoxyanthra[2,3-d][1,3]dioxole 7c [ 34 ]. 1 H NMR (200 MHz, C 6 D 6 ): 7.74 (s, 1H), 7.69 (d, J = 9.3 Hz, 1H), 7.54 (d, J = 2.5 Hz, 1H), 7.28 (dd, J = 9.3, 2.5 Hz, 1H), 7.23 (s, 1H), 7.14 (s, 1H), 5.35 (s, 2H), 3.79 (s, 3H), 3.55 (s, 3H) ppm.…”

“…Earlier, we obtained hetero (XR = OR, SR)-substituted acenes I via cyclization of diarylmethanol derivatives, i.e., ortho - O,O -acetals III (path a, Scheme 1 ) via oxo -Friedel–Crafts–Bradsher cyclization [ 32 , 33 , 34 ] or S,S -dithioacetals IV (path b, Scheme 1 ) via the thio -Friedel–Crafts–Bradsher cyclization [ 3 ]. In both heter o-Friedel–Crafts–Bradsher cyclizations, a new benzene ring, fused to two other (hetero)aromatic moieties, ArI and ArII, is formed in the acene I .…”

The First Example of the Friedel–Crafts Cyclization Leading to (10-Hydroxy-9,10-dihydroanthr-9-yl)phosphonium Salts without the Expected Bradsher Dehydration

“…Earlier, we elaborated a new approach to mono-hetero (Z = OR, SR)-substituted acenes IV via the hetero-Friedel-Crafts-Bradsher (F-C-B) cyclization of ortho-O,O-acetals, S,S-dithioacetals and O,S-thioacetals II obtained from diarylmethanols I [14][15][16][17]. In this reaction, a new benzene ring, fused to two other (hetero)aromatic moieties, ArI and ArII, is formed to give acenes IV (Scheme 1, path a).…”

Palladium immobilized on guanidine functionalized magnetic nanoparticles: a highly effective and recoverable catalyst for ultrasound aided Suzuki–Miyaura cross-coupling reactions

“…It is fascinating to know that organic transformations can occur in the presence of echoes of ultrasound pulses, and it effectively reduces the reaction times while also increasing the reactivity of chemical reactions. 4,5 Iron oxide nanoparticles, with their distinctive physicochemical properties and diverse uses, have attracted considerable attention in drug delivery, magnetic sensors, magnetic resonance imaging, and magnetic refrigeration. 6 Recently, they have been found to be promising solid support for the immobilization of transition metal nanoparticles for organic transformation.…”