36839-95-9Relevant academic research and scientific papers
Synthesis of Polycyclic Furan and Chromene Derivatives via Cascade Reactions Enabled by Cleavage of Multiple C(sp3)?F Bonds
Xie, Ting,Zhang, Chen,Zhang, Si-Xuan,Rao, Weidong,Xu, Haiyan,Shen, Zhi-Liang,Chu, Xue-Qiang
supporting information, p. 4736 - 4743 (2020/09/23)
The strong and unreactive C?F bond makes polyfluorocarbons extremely long-lived and potentially toxic. A successive selective and controllable C(sp3)?F functionalization of polyfluoroalkylated ketones with S- and O-nucleophiles to enable efficient synthesis of pharmaceutically important fluorine- and sulfur-containing polycyclic furan and chromene derivatives under transition metal-free conditions is demonstrated here. The combination of C?S/C?O coupling, aromatization, and cyclization cascade contribute to the accurate four/five C(sp3)?F bond cleavage at two different sites of perfluoroalkyl chain. The formation of reactive quinoid intermediates and the necessity of using TBAB (tetrabutylammonium bromide) as additive and Cs2CO3 as base were identified by detailed mechanistic studies. (Figure presented.).
Pd-catalyzed synthesis of α,β-unsaturated ketones by carbonylation of vinyl triflates and nonaflates
Zhang, Shaoke,Neumann, Helfried,Beller, Matthias
supporting information, p. 5938 - 5941 (2019/05/27)
A general and highly chemoselective Pd-catalyzed protocol for the synthesis of α,β-unsaturated ketones by carbonylation of vinyl triflates and nonaflates is presented. Applying the specific monophosphine ligand cataCXium A, the synthesis of various vinyl ketones as well as carbonylated natural product derivatives proceeds in good yields.
Radical Desulfur-Fragmentation and Reconstruction of Enol Triflates: Facile Access to α-Trifluoromethyl Ketones
Su, Xiaolong,Huang, Honggui,Yuan, Yaofeng,Li, Yi
supporting information, p. 1338 - 1341 (2017/01/24)
We report an efficient oxidative radical desulfur-fragmentation and reconstruction of enol triflates for the synthesis of α-CF3ketones. Preliminary mechanistic studies disclosed that oxidative fragmentation to release a CF3radical fr
Cp*Li as a base: application to palladium-catalyzed cross-coupling reaction of aryl-X or alkenyl-X (X=I, Br, OTf, ONf) with terminal acetylenes
Uemura, Minoru,Yorimitsu, Hideki,Oshima, Koichiro
, p. 1829 - 1833 (2008/09/18)
The reaction of aryl-X or alkenyl-X (X=I, Br, OTf, ONf) with terminal acetylenes in the presence of a catalytic amount of Pd(OAc)2 provided the alkynylated products in good yields by using Cp*Li (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) as a base.
PMHS-mediated couplings of alkynes or benzothiazoles with various electrophiles: Application to the synthesis of (-)-akolactone A
Gallagher, William P.,Maleczka Jr., Robert E.
, p. 6775 - 6779 (2007/10/03)
Polymethylhydrosiloxane (PMHS) in combination with CsF facilitates the cross-coupling of alkynes or benzothiazoles with an array of vinyl, styryl, and aryl halides or nonaflates as well as acid chlorides. Experimental and spectroscopic evidence indicates that these reactions involve the in situ generation of a siloxyl intermediate. These cross-couplings proceed relatively quickly at room temperature and under amine-free conditions. To demonstrate the applicability of the method, a total synthesis of the cyctotoxic butanolide (-)-akolactone A was carried out.
An expedient and stereoselective synthesis of alkenyl nonaflates from silyl enol ethers: Optimization, scope and limitations
Lyapkalo, Ilya M.,Webel, Matthias,Reissig, Hans-Ulrich
, p. 1015 - 1025 (2007/10/03)
The fluoride-catalysed reaction between silyl enol ethers 1 and nonafluorobutanesulfonyl fluoride (NfF) has been optimized, resulting in an expedient synthesis of the corresponding alkenyl nonaflates 3. Tetra-n-butylammonium fluoride, dried either with molecular sieves or with potassium fluoride, and potassium fluoride in the presence of dibenzo-18-crown-6 were the best and most practical catalysts for this process. The reaction allows the synthesis of a wide variety of cyclic and acyclic alkenyl nonaflates 3 in good to excellent yields. For E/Z isomeric alkenes the configuration of the double bond is essentially retained. Remarkably, enolates derived from methyl ketones also provide C-sulfonylation products 4 as a side product; the desired alkenyl nonaflates 31 and 3m could, however, be prepared in good yields by further optimization. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
One-pot transformation of silyl enol ethers into 1,3-dienes: In situ generation of alkenyl nonaflates and subsequent Heck reactions - Scope and limitations
Lyapkalo, Ilya M.,Webel, Matthias,Reissig, Hans-Ulrich
, p. 3646 - 3658 (2007/10/03)
Palladium-catalysed reactions between methyl acrylate and the isolated alkenyl nonaflates 2a, 2d and 2e proceed without difficulties, furnishing the desired 1,3-dienes 3, 14 and 15 in good yields. The use of other alkenyl nonaflates and olefins in this Heck reaction was also examined. The main purpose of this study was the development of an in situ generation of the required alkenyl nonaflates 2 from the corresponding silyl enol ethers 1 and their one-pot transformation into 1,3-dienes. Thus, the previously described fluoride-promoted exchange of the trimethylsilyl substituent of typical enol ethers 1 for a nonafluorobutylsulfonyl group was directly combined with the palladium-catalysed coupling step. This sequence allowed the efficient transformation of a variety of silyl enol ethers 1 into highly substituted 1,3-dienes in a practical one-pot procedure. The scope and limitations, together with the chemo- and stereoselectivity, of this process are discussed. A particular intriguing example involves a one-pot synthesis of silyl enol ether 1j by means of a Diels-Alder reaction, subsequent nonaflation and a Heck reaction with tert-butyl acrylate, furnishing the highly functionalised 1,3-diene 30 in good overall yield. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
Heck Reactions Starting from Silyl Enol Ethers - A Simple One-Pot Nonaflation-Coupling Procedure for the Synthesis of 1,3-Dienes
Webel, Matthias,Reissig, Hans-Ulrich
, p. 1141 - 1142 (2007/10/03)
Starting from silyl enol ether 4 the corresponding alkenylnonaflate 5 was generated by treatment with nonafluorobutanesulfonyl fluoride (NfF) and a catalytic amount of tetra-n-butylammonium fluoride (TBAF). By Pd-catalysis 5 was directly Heck-coupled with
Preparation of Vinylsulfonates from Trimethylsilyl Enol Ethers - Synthetic Consequences of a Remarkable Cation Effect
Hirsch, Elisabeth,Huenig, Siegfried,Reissig, Hans-Ulrich
, p. 3687 - 3696 (2007/10/02)
The C/O-selectivity observed in the sulfonylation of the enolate ion 5 with benzenesulfonyl fluoride depends strongly on the nature of the gegenion.Li+ yields the β-oxosulfone 3 by C-sulfonylation exclusively.The fraction of O-sulfonylation is increased with the size of the cation, yielding the vinylsulfonates 6b exclusively in the presence of Cs+ or quaternary ammonium ions.From this behaviour a regio- and stereoselective synthesis of vinylsulfonates is developed starting from the corresponding trimethylsilyl enol ethers.
