PPh3/Selectfluor‐Mediated Transformation of Carboxylic Acids into Acid Anhydrides and Acyl Fluorides and Its Application in Amide and Ester Synthesis

• Published in: European journal of organic chemistry Vol. 2019; no. 34; pp. 5998 - 6002
• Main Authors: Yang, Zhen, Chen, Siwei, Yang, Fang, Zhang, Chenxi, Dou, You, Zhou, Qiuju, Yan, Yizhe, Tang, Lin
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 15.09.2019; Wiley Subscription Services, Inc
• Subjects: Acid anhydrides; Acidic oxides; Acyl fluorides; Alcohols; Amides; Amines; Carboxylic acids; Chemistry; Chemistry, Organic; Esters; Fluorides; Physical Sciences; Reagents; Science & Technology; Selectfluor; Triphenylphosphine; REAGENT; MITSUNOBU; ACYLATION; TRIFLUORIDE; Acyl fluorides; Carboxylic acids; FLUORINATION; Triphenylphosphine; Acid anhydrides; MILD; ALCOHOLS; Selectfluor; DEHYDRATION; CHLORIDES; EFFICIENT
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201901092

By taking the advantage of PPh3/Selectfluor system, carboxylic acids are efficiently converted into the pivotal intermediates acyloxyphosphonium ions that can selectively react with a second carboxylic acid or fluoride to in situ yield the corresponding acid anhydrides or acyl fluorides. The developed protocol features commercially availabile reagents, no involvement of base, room temperature conditions, and simple experimental procedure. Additionally, various amides or esters are readily achieved, respectively, with the addition of amines or alcohols. An efficient synthesis of acid anhydrides or acyl fluorides mediated by PPh3/Selectfluor synstem is reported. Mechanistic studies show that the reaction proceeds through active species of acyloxyphosphonium ions, which can be quickly converted into the final products in situ by a second carboxylic acid or F–.