Regioselective alkynylation of 2-aryl-4-chloro-3-iodoquinolines and subsequent arylation or amination of the 2-aryl-3-(alkynyl)-4-chloroquinolines

Studies of one-pot double couplings on dibromoquinolines

“…(Scheme 4) For the most part, these reactions feature a standard S N Ar reaction with either an amine or a phenol for the first “coupling” and then a Suzuki coupling at the remaining halide. 16 …”

Halogenated Quinolines as Substrates for the Palladium‐Catalyzed Cross‐Coupling Reactions to Afford Substituted Quinolines

“…Sonogashira reaction was used before on 2‐(4‐chlorophenyl)‐4‐iodoquinoline with phenylacetylene in triethylamine at reflux in the presence of a Pd(PPh 3 ) 4 /CuI mixture to afford 2‐(4‐chlorophenyl)‐4‐(phenylethynyl)quinoline in 72% yield [54]. PdCl 2 (PPh 3 ) 2 /CuI‐catalyzed Sonogashira coupling of 2‐aryl‐4‐chloro‐3‐iodoquinolines 43 with terminal acetylenes (1.5 equiv) in triethylamine afforded the 2‐aryl‐3‐(alkynyl)‐4‐chloroquinolines 44 as sole products (Scheme 14) [55, 56].…”

“…The 2‐aryl‐3,4‐bis(alkynyl)quinoline derivatives 45 were prepared in a single‐pot operation from 43 using 2.5 equiv of terminal acetylenes in dioxane–water under reflux (Scheme 15) [56].…”

“…A similar approach was used recently on systems 44 which were further subjected to Pd(PPh 3 ) 4 ‐catalyzed Suzuki cross‐coupling with trans ‐phenylvinylboronic acid or 4‐fluorophenylboronic acid in the presence of K 2 CO 3 and PCy 3 as ligand in aqueous dioxane at 80°C to afford the 2,3,4‐trisubstituted quinolines 73a , 73b , 73c , 73d , 73e , 73f in reasonable yields (Scheme 27) [56]. As the reaction failed to take place in the absence of the ligand, it was concluded that an alkylphosphine ligand counteracts the inhibitory effect of the extra PPh 3 generated from dissociation of Pd(PPh 3 ) 4 to Pd(0)(PPh 3 ) 2 to speed up the oxidative addition step.…”

Synthesis and Photophysical Property Studies of the 2,6,8-Triaryl-4-(phenylethynyl)quinazolines

“…However, Sonogashira cross-coupling of 6-bromo-2,4-dichloroquinazoline with stoichiometric amount of terminal alkynes led to exclusive replacement of the 4-chloro atom [5]. During our research on the development of novel polysubstituted heterocycles [8,9], we became interested in the synthesis of polysubstituted quinazolines in which the electron-deficient quinazoline framework is linked to the 4-phenyl ring via π-conjugated spacer and to the 6-and 8-aryl rings directly to comprise donor-π-acceptor systems. We envisioned that the 2-aryl-6,8-dibromo-4-chloroquinazolines represent suitable candidates for sequential Pd-catalyzed Sonogashira and Suzuki cross-coupling to afford the requisite polysubstituted quinazolines with potential photophysical properties.…”