New procedures for the selective synthesis of 2(2H)-pyranone derivatives and 3-aryl-4-iodoisocoumarins
摘要:
5-Iodo-2(2H)-pyranone derivatives have been selectively synthesized by reaction of stereodefined methyl 2-en-4-ynoates with iodine in MeCN, CH2Cl2 or C6H6 at 20degreesC (Method C) or by treatment of these esters with ICl in CH2Cl2 at 20degreesC (Method B). Methods B and C proved also to be suitable for the preparation of 3-aryl-4-iodoisocoumarins from the corresponding methyl 2-(arylethynyl)benzoates. Interestingly, the high selectivity of iodolactonization of stereodefined methyl 2-en-4-ynoates by Method B allowed preparation in moderate yields of 2(2H)-pyranone derivatives by a one-pot sequence of iodolactonization and Stille-type reactions. (C) 2002 Elsevier Science Ltd. All rights reserved.
Brønsted Acid Promoted Sulfenylacyloxylation of Alkynes: Access to 4‐Sulfenylisocoumarins
作者:Arijit Saha、E. Ramesh、Akhila K. Sahoo
DOI:10.1002/adsc.202200761
日期:2022.10.18
Presented herein is the Brønsted acid (MsOH) mediated electrophilic sulfenylacyloxylation of o-alkynylbenzoates via alkyne activation by in-situ formed sulfonium cations from bench-stable N-thioaryl/alkyl-succinimides followed by the intramolecular regioselective cyclization. The transformation provides access to structurally diverse 4-sulfenylisocoumarins in 77–98% yields with broad functional group