Simple and Practical Conversion of Benzoic Acids to Phenols at Room Temperature

Abstract

Phenols are important organic molecules because they have found widespread applications in many fields. Herein, an efficient and practical approach to prepare phenols from benzoic acids via simple organic reagents at room temperature is reported. This approach is compatible with various functional groups and heterocycles and can be easily scaled up. To demonstrate its synthetic utility, bioactive molecules and unsymmetrical hexaarylbenzenes have been prepared by leveraging this transformation as strategic steps. Mechanistic investigations suggest that the key migration step involves a free carbocation instead of a radical intermediate. Considering the abundance of benzoic acids and the utility of phenols, it is anticipated that this method will find broad applications in organic synthesis.

Simple and Efficient Aromatic C–H Oxazolination

“…Our laboratory has intense interest on the transformations of benzoic acids . Therefore, a simple, practical, and cost-effective approach to access diverse substituted benzoic acids without specialized high-pressure equipment from readily available arenes is desired.…”

“…Our laboratory has intense interest on the transformations of benzoic acids. 33 Therefore, a simple, practical, and costeffective approach to access diverse substituted benzoic acids without specialized high-pressure equipment from readily available arenes is desired. In this context, the dream reaction would be that regular arene (not only phenol) directly reacts with CO 2 (ideally 1 atm) to construct the C−C bond under simple and practical reactions (Figure 2A).…”

“…Following orthodirected fluorination and hydrolysis, 36 was transformed into 37 (62%). By using the procedure previously developed by our laboratory, 33 benzoic acid 37 was converted into substituted phenol 38 (58%). Following triflation and Suzuki coupling, 39 was obtained in high yield (95% and 96% for each step).…”

Recent Advances in Carbon‐Nitrogen/Carbon‐Oxygen Bond Formation Under Transition‐Metal‐Free Conditions

“…Radical scavenging experiments indicated that an anionic pathway was involved in the CÀ CN bond cleavage process. Recently, Jamieson and co-workers developed a new amide bond formation strategy via the rearrangement of highly reactive nitrile imines (NI) derived from N-2-nitrophenyl hydrazonyl bromides (135), delivering 136 as active intermediates (Scheme 25). [75] This strategy was applicable to the synthesis of primary, secondary and tertiary amides (137, totally 42 examples, Up to 99 % yields).…”

“…In the same year, the Liu group reported a simple and practical procedure for the conversion of benzoic acids bearing various functional groups (233) to the corresponding phenols (234) under mild conditions with a broad substrate scope via a peroxide activation process (Scheme 49a). [135] In this work, the readily available 3-choroperoxybenzoic acid (m-CPBA, for electron-rich benzoic acids) and Na 2 CO 3 • 1.5H 2 O 2 (for electron-deficient substrates) were utilized, affording desired products in 27-90 % yields. Based on the mechanistic studies and related literatures, one possible mechanism involving an acid-promoted [1,2]-migration step was proposed, with benzoic acid as the typical substrate (Scheme 49b).…”