Pd(ii) catalyzed ortho C–H iodination of phenylcarbamates at room temperature using cyclic hypervalent iodine reagents

Abstract

A novel approach to access ortho iodinated phenols using cyclic hypervalent iodine reagents through palladium(II) catalyzed C-H activation has been developed through weak coordination. The reaction showed excellent regioselectivity, reactivity and good functional group tolerance. A unique mechanism was proposed.

Nickel(II)‐Mediated Regioselective CH Monoiodination of Arenes and Heteroarenes by using Molecular Iodine

“…In addition, these reports did not mention the iodination of heteroarenes. Rao and co‐workers have reported12s the Pd(II)‐catalyzed ortho ‐CH iodination of phenyl carbamate by using a hypervalent iodine reagent. Very recently, Shi and co‐workers have disclosed9h a method for the ortho ‐ halogenation of benzamide by N ‐halosuccinamides (NCS, NBS, NIS) using a Cu(II) catalyst.…”

ortho‐Lithiation Reactions of O‐(3,n‐Dihalophenyl) N,N‐Diethylcarbamates: Synthesis of Dihalosalicylamides and 2,3,n‐Trihalophenol Derivatives

“…To further demonstrate the synthetic usefulness of iodinated carbamates 6 and 7 , we selected iodo derivatives 6e and 7c and smoothly transformed them into alkynyl‐ and aryl‐functionalized products 8 and 9 , respectively, under standard Sonogashira and Suzuki cross‐coupling conditions (Scheme ). In addition, the cyanation reaction of 6f with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) gave rise to O ‐(2‐cyanophenyl) carbamate 10 in good yield .…”

Transition Metal‐Catalyzed Directing‐Group‐Assisted C−H Activation of Phenols

“…Rao and co-workers reportedaPd-catalyzed ortho-iodination of phenol carbamates by using 1-methoxy-1,2-benziodoxole-3(1H)-one( I III ÀOMe) as an iodination reagent. [31] The method displayed high functional group tolerance, av ariety of phenol carbamates underwent ortho-iodination process with high selectivitya nd good yields. The authors suggested that ap ossible Pd II -Pd IV catalytic cycle might be involved in this reaction.…”

“…However, the ortho ‐iodination of phenol carbamates by treatment with N ‐iodine‐succinimide was not successful. Rao and co‐workers reported a Pd‐catalyzed ortho ‐iodination of phenol carbamates by using 1‐methoxy‐1,2‐benziodoxole‐3(1 H )‐one (I III −OMe) as an iodination reagent . The method displayed high functional group tolerance, a variety of phenol carbamates underwent ortho ‐iodination process with high selectivity and good yields.…”