Hypervalent iodine(III)-mediated decarboxylative acetoxylation at tertiary and benzylic carbon centers

Abstract

The decarboxylative acetoxylation of carboxylic acids using a combination of PhI(OAc)2 and I2 in a CH2Cl2/AcOH mixed solvent is reported. The reaction was successfully applied to two types of carboxylic acids containing an α-quaternary and a benzylic carbon center under mild reaction conditions. The resulting acetates were readily converted into the corresponding alcohols by hydrolysis.

PhI(OTf)2 Does Not Exist (Yet)**

“…Regarding the intermediate, which is consistent with the PhI(OTf) 2 spectrum proposed by Zhdankin, in both CDCl 3 and CD 2 Cl 2 , the ‐ ortho aryl protons in PhI(OAc) 2 resonate at 8.10 ppm [22] . For PhI(OAc)(OTf) the ‐ ortho protons resonate at a chemical shift of 8.25 ppm [17] .…”

“…[21] Regarding the intermediate, which is consistent with the PhI(OTf) 2 spectrum proposed by Zhdankin, in both CDCl 3 and CD 2 Cl 2 ,t he -ortho aryl protons in PhI(OAc) 2 resonate at 8.10 ppm. [22] For PhI(OAc)(OTf) the -ortho protons resonate at a chemicals hift of 8.25 ppm. [17] It would be expected that another substitution of acetate for more electron poor triflate would lead to af urther downfield chemical shift for these protons, thus as ignal at 8.2 ppm is not consistent with PhI(OTf) 2 .T he observation that not all the TMS-OTf is consumed in the reaction is also inconsistentw ith formation of PhI(OTf) 2 .I ns ummary,P hI=Or eacted with two equivalents of TMS-OTf does not generate as olution of PhI(OTf) 2 based on 1 HNMR data.…”

Decarboxylation‐Initiated Intermolecular Carbon‐Heteroatom Bond Formation

“…on photodecarboxylative acetoxylation with the combination of PhI(OAc) 2 and I 2 was initially only amenable to uronic acids and α‐amino acids (Scheme 29). [257–260] The substrate scope of this metal‐free system was recently extended to tertiary and benzylic carboxylic acids by Minakata and co‐workers [290] . Tunge et al.…”

Transition‐Metal‐Free Synthesis of N‐Substituted Phenanthridinones and Spiro‐isoindolinones: C(sp2)−N and C(sp2)−O Coupling through Radical Pathway

“…To our delight, when the reaction was conducted using phenyliodine(III) diacetate (PIDA) instead of PIFA, a novel spiro‐ iso indolinone 4a was realized in 45% yield involving the de‐aromatization and acetylation of the phenyl ring . The addition of potassium acetate and sodium tert ‐butoxide to the reaction mixture led to the improved (58%) yield of 4a (Scheme ).…”