Peroxydisulfate‐Mediated Transition‐Metal‐Free Oxidative C(sp³)−H Bond Lactonization

Abstract

An inexpensive, powerful, and eco-friendly method for transition-metal-free oxidative C(sp 3 )À H bond lactonization was developed using sodium peroxydisulfate as the sole oxidant. The cyclization of 2-alkylbenzoic acids containing a primary, secondary or tertiary carbon at the benzylic position proceeded smoothly, affording a variety of lactone derivatives. Furthermore, various functional groups such as halogen, cyano, nitro and hydroxy groups were tolerated under the reaction conditions.

Organocatalytic enantioselective synthesis of phthalans via Wittig/oxa‐Michael cascade reaction

“…1,3‐Dihydro‐2‐benzofuran‐1‐ol 1 as the starting material for the AIOM reaction was gladly synthesized from o ‐methylbenzoic acid 2 in two steps (Scheme 2). Phthalide 3 with substituents in their aromatic ring was obtained from the oxidative CH bond lactonization of o ‐methylbenzoic acid 2 using peroxydisulfate as the oxidant in the presence of tetrabutylammonium bromide (TBAB) 8 . The reduction of phthalide 3 using DIBAL‐H produced the desired 1,3‐dihydro‐2‐benzofuran‐1‐ol 1 including 2‐(hydroxymethyl)benzaldehyde 4 tautomer in good yields 9 …”

Critical Ligand and Salt Effects in Organomagnesiate‐Promoted 3,3‐Disubstituted Phthalides Synthesis from 2‐Iodobenzoate Derivatives

“…3‐Methyl‐3‐propyl‐(3 H )‐isobenzofuran‐1‐one (2n) : [14] Compound 2n was prepared according to the general procedure B using ethyl‐2‐iodobenzoate 1a (69 mg, 0.25 mmol) and 2‐pentanone (35 mg, 0.40 mmol). The title compound was obtained after flash chromatography as yellow oil.…”

“…Many of these methods are non‐convergent synthetic routes and rely on intramolecular cyclization, requiring relatively complex syntheses of the starting materials in order to bring diversity to the final phthalides. For instance, as shown in Scheme 1, the first route involved ortho ‐alkyl benzoic acids followed by oxidation of the alkyl chain and ring closing (Scheme 1A [14] ). [15–17] The second was a copper‐catalyzed cyclization of ortho ‐bromo‐benzylalcohols (Scheme 1B) [18] .…”

Bifunctional Iodoazolium Salts: Searching for Cooperation Between Halogen Bonding and Hydrogen Bonding

“…Additional references cited within the Supporting Information. [36][37][38][39][40][41][42][43][44][45][46][47][48]…”