Silver-Mediated Decarboxylative Fluorodiiodination of Alkynoic Acids: Synthesis of Regio- and Stereoselective Fluoroalkenes Aravindan Jayaraman and Sunwoo Lee* Department of Chemistry, Chonnam National University, Gwangju 61186, Republic of Korea * S Supporting Information ABSTRACT: A variety of arylalkynoic acids reacted with 1,3- diiodo-5,5-dimethylhydantoin and HF·pyridine in the presence of AgOAc to provide the corresponding 1-fluoro-2,2-diiodovi- nylarenes in good yields and high regioselectivity. In addition, Pd-catalyzed cross-coupling reaction of 1-fluoro-2,2-diiodovi- nylarenes afforded diaryl coupling products in the Suzuki reaction and monoaryl coupling products with high stereo- selectivity in the Hiyama reaction. It was found that C-F- activated borylation of fluoroalkenes using Pd catalyst afforded the vinylboranes with good yields. M any biological and medicinal products, as well as important functional materials, contain the fluorine functionality. 1 Substitution of hydrogen with fluorine in organic materials can dramatically change the reactivity and the chemical, physical, and biological properties of the corresponding compounds. 2 As a consequence, fluorinated compounds have recently gained considerable attention in various fields, and the number of methodologies introducing the fluorine functionality into organic compounds has increased drastically over the last few decades. 3 Fluoroalkene, one of the numerous fluorine-containing compounds, is an important structural motif found in many bioactive compounds and is a useful building block. 4 A variety of synthetic methods for fluoroalkenes have been reported in the literature, and hydrofluorination of alkynes is one such straightforward method (Scheme 1a). 5 Sadighi first reported hydrofluorination of alkynes using Au catalyst to furnish fluoroalkenes in good yields. A number of Au-catalyzed hydrofluorination reactions of alkynes have been developed by several groups. In addition, it was reported that alkynes having a carbonyl group could be converted into the corresponding fluoroalkenes under metal-free or copper catalysis conditions (Scheme 1b). 6 Moreover, fluoroalkene derivatives 1,2-bromofluoro- and 1,2-fluoroiodoalkenes have received considerable attention as useful fluorinated building blocks because these vinyl bromides and iodides can be further transformed into versatile molecules via cross-coupling reactions (Scheme 1c). Jiang demonstrated that 1,2-bromofluoroalkenes could be synthesized by the reaction of terminal alkynes with NBS/AgF. 7 Synthesis of 1,2- fluoroiodoalkenes was accomplished by the fluoroiodination of alkynes employing HF-based reagents along with the iodine reagents such as I 2 , Tol-IF 2 , IF 5 , PhIO, and 1,3-diiodo-5,5- dimethylhydantoin (DIH). 8 In contrast, much less attention has been paid toward gem-dihalo-substituted fluoroalkenes, although in theory, they are highly likely to be employed as coupling partners in the cross-coupling reactions for the preparation of mono- and disubstituted fluoroalkenes. It has been reported that the preparation of gem-dibromo- and gem- dichlorofluoroalkenes from aldehydes requires a multistep process (Scheme 1d). 9 Therefore, simple and one-step synthetic methods are required. Received: February 17, 2019 Published: April 12, 2019 Scheme 1. Synthesis of Fluoroalkenes Letter pubs.acs.org/OrgLett Cite This: Org. Lett. 2019, 21, 3485-3489 © 2019 American Chemical Society 3485 DOI: 10.1021/acs.orglett.9b00597 Org. Lett. 2019, 21, 3485-3489 Downloaded via CHONNAM NATL UNIV on May 17, 2019 at 04:59:07 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.