C-8-Selective Allylation of Quinoline: A Case Study of β-Hydride vs β-Hydroxy Elimination

Abstract

An unprecedented C(8)-H bond allylation of quinoline with allyl carbonate and allyl alcohol catalyzed by Cp*Co(III) using a traceless directing group via β-oxygen and β-hydroxy elimination is described. This site-selective allylation reaction proceeds smoothly with various functional group tolerance including quinoxaline and phenanthridine. Under the nonoxidative reaction conditions, the difference in selectivity between Rh(III) and Co(III), which proceeds through β-hydride and β-hydroxy elimination using allyl alcohol, is shown for the first time.

Comparison of the Reactivities and Selectivities of Group 9 [Cp*MIII] Catalysts in C−H Functionalization Reactions

“…[26] When [(Cp*CoI 2 ) 2 ] was used as the catalyst in the presence of AgOTfa nd NaOPiv, allylation selectively took place at the C8 positiono fthe quinoline N-oxides with moderate-to-excellent E selectivities.I nc ontrast, b-aryl ketones (rather than allylated compounds) were obtained when [(Cp*RhCl 2 ) 2 ]w as used instead of [(Cp*CoI 2 ) 2 ] under otherwise-identical conditions. [26] When [(Cp*CoI 2 ) 2 ] was used as the catalyst in the presence of AgOTfa nd NaOPiv, allylation selectively took place at the C8 positiono fthe quinoline N-oxides with moderate-to-excellent E selectivities.I nc ontrast, b-aryl ketones (rather than allylated compounds) were obtained when [(Cp*RhCl 2 ) 2 ]w as used instead of [(Cp*CoI 2 ) 2 ] under otherwise-identical conditions.…”

RhIII‐Catalyzed Direct C8‐Arylation of Quinoline N‐Oxides using Diazonaphthalen‐2(1H)‐ones: A Practical Approach towards 8‐aza BINOL

“…In contrast, introductiono ff unctional groups at the remote C8 position of quinoline N-oxide is startedg etting explored very recently. [13] In its itinerary,d irect C8-arylation of quinoline N-oxide is also one of the very important area that needs to be investigated. [14] Since the discovery of Rh II -catalyzed direct C8-arylation of quinolineb yC hang group, [14a] continuous efforts are there to developn ew methods for direct arylation of quinoline Noxidesa ti ts C8 position.…”

“…Though the reaction workedu nder various solvents (entries 2-5), butD CE was found to be the best among them (entry 6) with 92 %i solated yield of desired product.F urther scrutiny of carboxylic acids having less or more bulk as additive did not improve the isolated yield of 3a (6)(7)(8). For more augmentation in yield of 3a, variouss ilver salts were tested but no further improvement in yield was realized (entries [9][10][11][12][13]. The yield of the desired product decreased to 65 %w hen the reaction temperature lowered to 60 8C( entry 15).…”

Template‐Assisted meta‐C−H Alkylation and Alkenylation of Arenes

“…[4] In 2012, Sigman and co-workers reported the breakthrough discovery of the generation of ar emote quaternary stereocenter using aredox relay strategy of alkenyl alcohols with aryl diazonium salts. [6] In this work, we intended to incorporate allyl alcohol and allyl benzyl ether at the meta-position of arene through apalladium-catalyzed approach (Figure 1). [6] In this work, we intended to incorporate allyl alcohol and allyl benzyl ether at the meta-position of arene through apalladium-catalyzed approach (Figure 1).…”