Application of titanium catalysts for the syntheses of heterocycles

Applications of metal and non-metal catalysts for the synthesis of oxygen containing five-membered polyheterocylces: a mini review

“…Miki and co-workers synthesized (2-furyl)-cyclopropanes by transition-metal-catalyzed cyclopropanation of alkenes with 1-benzoyl cis-1-en-3-yne (Scheme 5) [109,110]. Many transition-metal complexes, like Mo(CO) 5 (THF), Cr(CO) 5 (THF), [RuCl 2 (CO) 3 ] 2 , W(CO) 5 (THF), palladium chloride, [RhCl-(cod)] 2 , and platinum chloride, acted as catalysts for this transformation [78][79][80][81][82][83][84][85][86][87]111].…”

“…The substrates such as 5-(2-furyl)-1-alkynes substituted at C-5 of the furan were cyclized to provide the phenols. The reaction occurred via an intramolecular [4 + 2] cycloaddition which was promoted by the η 2 -coordination of gold(III) chloride to the alkyne [78][79][80][81][82][83][84][85][86][87]121].…”

“…Davies and co-workers [293] reported that aryldiazoacetates underwent asymmetric intramolecular reaction in the presence of Rh 2 -(S-DOSP) 4 to afford the carbon-hydrogen insertion products (Scheme 47). The enantioselectivity strongly depends on the site of the carbon-hydrogen activation; the highest enantioselectivity was reported for insertion into the methyne carbon-hydrogen bond [78][79][80][81][82][83][84][85][86][87].…”

“…Many protocols have been investigated for the synthesis of heterocycles. These protocols for the formation of heterocyclic compounds involve carbon-nitrogen bondforming reactions such as nucleophilic substitution, reductive amination, or dipolar cycloaddition for ring closure [74][75][76][77][78][79][80][81][82][83][84][85][86][87]. Although various protocols have been developed, their functional group tolerance and substrate scope is often limited.…”