C–S Bond Activation of Thioesters Using Platinum(0)

Abstract

b S Supporting Information ' INTRODUCTIONCarbonÀsulfur bond activation by transition-metal complexes has been extensively studied for decades. 1 In particular, CÀS bond activation of thiophene has received a great deal of attention in order to understand the mechanism of the hydrodesulfurization (HDS) process. 2 CarbonÀsulfur bond activation of thioesters has also received a great deal of interest in recent years. For example, in 1989 Shaver and co-workers reported chelate-assisted CÀS bond activation of 8-quinoline thioesters using Rh(PPh 3 ) 3 Cl. 3 Oxidative addition of thioesters to Fe(0) was reported by Rauchfuss and co-workers, 4 and CÀS bond activation of thioesters followed by insertion of 1-alkyne and CÀC elimination by Pt complexes has been studied by the Kuniyasu group (eq 1). 5 In the case of Pd complexes, R 1 SR 2 was formed under similar reaction conditions. CarbonÀsulfur bond activation of thioesters by (L 2 )Ni 0 (L 2 = dppe, depe) has been recently reported by Riordan and coworkers (eq 2). 6 The reaction was not clean, and a mixture of products including (L 2 )Ni(Me)(SAr), Ni(L 2 ) 2 , (L 2 )Ni(CO) 2 , and (L 2 )Ni(SAr) 2 was formed at room temperature. At low temperature (À78°C), acylnickel thiolates were detected by 13 P NMR spectroscopy. Thioesters having the electron-deficient substituent C 6 F 5 and an electron-rich phosphine ligand produced alkylnickel(II) thiolates in better yield. Of related interest, Yamamoto observed reversible arylÀsulfur cleavage in the reaction of Ph 2 S with [Ni(dmpe)]. 7Earlier work in our group showed that the fragment [Pt(dippe)] was active in CÀS bond cleavage of thiophenes, 8 and the selectivity for cleavage of one or the other CÀS bond as a function of substitution was examined. Here, an extension to the CÀS bond activation of cyclic and acyclic thioesters is examined. Evidence is provided for sulfurÀacyl CÀS bond oxidative addition followed by decarbonylation and subsequent CÀS reductive elimination. β-Hydrogen elimination occurs to form the olefin, when possible. Reaction with a second molecule of thioester can lead to additional products via a Pt IV intermediate. ' RESULTS AND DISCUSSIONReaction with MeC(O)SMe. Treatment of (dippe)Pt(NBE) 2 (1; NBE = norbornene) with 5 equiv of S-methyl thioacetate in benzene at 100°C for 25 min afforded the complex (dippe)Pt-(C(O)Me)(SMe) (2a) in good yield (eq 3). Complex 2a was isolated as an off-white solid and characterized by 1 H, 13 C{ 1 H}, and 31 P{ 1 H} NMR spectroscopy and X-ray crystallography ( Figure 1). The 31 P{ 1 H} NMR spectrum of complex 2a appeared as two doublets with platinum satellites at δ 60.14 (J PÀP = 3.9 Hz, J PtÀP = 3018 Hz) and 57.69 (J PÀP = 3.9 Hz, J PtÀP = 1413 Hz). These platinumÀphosphorus couplings are typical for phosphorus trans to thiolate and sp 2 -carbon ligands. 9 The structure of 2a shows typical square-planar Pt II with a PtÀacyl bond length of 2.099(7) Å and a PtÀSMe distance of 2.338(2) Å.Treatment of (dippe)Pt(NBE) 2 with 10 equiv of S-methyl thioacetate in p-xylene-d 10 at 16...

The Versatile Behavior of Platinum Alkyne Complexes towards XeF2: Formation of Fluorovinyl and Fluorido Complexes

“…The crystalso fc ompound 6 are twinneda nd have been refineda s at wo domain twin. [98] The 195 Pt satellites overlap in the 1D spectrum with the signals for the isopropyl group, but a 1 H, 13 CHMQC spectrum reveals them to have ac oupling constant of 2 J(Pt,H) = 64 Hz. The platinum metal centere xhibits an approximately square-planar geometry with the P1, N1, C11, and C12 atoms occupying the four coordination sites.…”

“…The unit cell of compound 7 ·0 .25 CH 2 Cl 2 containst wo independent molecules in the asymmetric unit, which exhibit comparable bond lengths anda ngles. [98] As expected, the bite angle P1-Pt1-N1o fc ompound 7 with 84.55(6)8 is smaller in comparison to the one in compound 3.T reatmento fc ompound 4 with AgF and CF 3 SiMe 3 under sonication led to the generation of the trifluoromethyl complex [Pt(PhC=CFPh)(CF 3 ){k 2 -(P,N)-iPr 2 PC 2 H 4 NMe 2 }] (8). The platinum atom is coordinated in as quare-planar geometry by the P1 and N1 atoms of the iPr 2 PC 2 H 4 NMe 2 ligand as well as by the C11a nd C12 atoms of the methyl and b-fluo- rovinyl ligand.The Pt1ÀN1 and Pt1ÀC12 bond lengths are similar,w hereas the Pt1ÀP1 bond lengtho f2 .2708(6) is slightly elongated compared to the bond length in compound 3.T he Pt1ÀC11b ond length of 2.131 (2) is in good agreement with the one found fort he PtÀCb ond (i.e.,2 .112(3) )i nt he complex [Pt(CH 3 )(SEt)(dippe)] (dippe = 1,2-bis(diisopropylphosphino)ethane).…”

Metal‐Catalyzed Synthesis and Use of Thioesters: Recent Developments

“…Indeed, SET steps are involved in the photoredox-catalyzed reactions. Fundamental insight into such catalytic systems, such as studies into the elementary organometallic steps [107] or kinetica nalysis, could be useful in the development of further improved variations of the knowno ro fc onceptual new transformations of thioesters.…”

Mass spectrometric and theoretical studies on dissociation of the CS bond in the benzenesulfonic acid and benzenesulfinic acid anion series: Homolytic cleavage vs heterolytic cleavage

“…Activation and cleavage of the CAS bond is a critical component in the study of the organosulfur chemistry [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. A case for example is the hydrodesulfurization (HDS) process in the chemical industry.…”