137515-74-3Relevant academic research and scientific papers
Cyclic tetramers of a five-membered palladacycle based on a head-to-tail-linked isocyanate dimer and their reactivity in cyclotrimerization of isocyanates
Lee, Seon Gye,Choi, Keun-Young,Kim, Yong-Joo,Park, Sujin,Lee, Soon W.
, p. 6537 - 6545 (2015/04/14)
Reactions of [Pd(styrene)(PR3)2], generated from trans-[PdEt2(PR3)2] and styrene, with 2 equiv. of benzyl isocyanate in THF at room-temperature afforded unusual cyclic Pd-tetramers of five-membered rings consisting of organic isocyanate dimers and palladium, [Pd(PR3){-C(O)N(R)C(O)N(R)-}]4 (PR3 = PMe3, 1; PR3 = PMe2Ph, 2). Additionally, a cyclic trimer, (RNCO)3, 3 (R = benzyl) was produced as a catalytic product. Treatment of the cyclic tetramer (1) with 4 equiv. of chelated phosphine, such as (1,2-bis(diethylphosphino)ethane) (DEPE) or (1,2-bis(dimethylphosphino)ethane) (DMPE), readily caused conversion to a metallacyclic cis-form, [Pd{N(R)C(O)N(R)C(O)}(P ～ P)] (P ～ P = DEPE, 4; P ～ P = DMPE, 5) in quantitative yields. In contrast, reactions of Pd(0)-PR3 with 2 equiv. of Ar-NCO (Ar = Ph, p-tolyl, p-ClC6H4) afforded metallacyclic complexes having a dimeric isocyanato moiety, cis-[Pd{C(O)N(Ar)-C(O)N(Ar)}(PR3)2] (PR3 = PMe3 Ar = C6H5, 6; p-MeC6H4, 7; p-Cl-C6H4, 8; PR3 = PMe2Ph, Ar = p-Cl-C6H4, 9). Treatment of the palladacyclic complex (8) with an equimolar amount of chelated phosphine such as DEPE readily caused conversion to a palladacyclic cis-form, [Pd{N(Ar)C(O)N(Ar)C(O)}(DEPE)], 10 in quantitative yield. The catalytic cyclotrimerization of benzyl isocyanate to [Pd(styrene)(PMe3)2] was achieved by varying the molar ratio of R-NCO (R = benzyl). In addition, catalytic cyclotrimerization was performed from the five-membered palladacyclic complexes or the Pd(0)-PR3 complex with excess Ar-NCO. This journal is
A new reactive system for catalytic bis-silylation of acetylenes and olefins
Ozawa, Fumiyuki,Sugawara, Mitsuru,Hayashi, Tamio
, p. 3237 - 3243 (2008/10/08)
Reaction of diphenylacetylene (1a) with Me3SiSiF2Ph (1 equiv) in toluene in the presence of a palladium catalyst (1 mol %) generated in situ by mixing [Pd(η3-allyl)Cl]2 and PMe2Ph (2.2 equiv/Pd) was completed in 1.4 h at room temperature to give the bis-silylation product (Z)-1-(difluorophenylsilyl)-1,2-diphenyl-2-(trimethylsilyl)ethene (2a) in 95% yield. In similar catalytic systems, a variety of acetylenes and olefins, including 3-hexyne, 1-phenyl-1-propyne, phenylacetylene, 1-octyne, norbornene, styrene, and 1-octene, were bis-silylated in 64-96% yields. The highly reactive nature of the present catalytic system was studied in stoichiometric systems. The presumed intermediates trans-Pd(SiMe3)(SiF2Ph)L2 (L = PMe3 (4a), PMe2Ph (4b)) were prepared by oxidative addition of Me3SiSiF2Ph toward Pd(styrene)L2 complexes (L = PMe3 (3a), PMe2Ph (3b)). Complex 4b reacted with diphenylacetylene (3 equiv) in toluene-d8 at -20°C to give the bis-silylation product (Z)-2a in 82% yield together with Pd(PhC≡CPh)(PMe2Ph)2 (93%). Treatment of 4a with dimethyl acetylenedicarboxylate (1 equiv) in toluene at -20°C instantly formed a palladium(0) complex coordinated with bis-silylated olefin, Pd{(Z)-(MeO2C)(Me3Si)C=C(SiF2Ph)(CO 2Me)}(PMe3)2 (6). The structure of 6 was determined by an X-ray diffraction study. Crystal data for 6·THF: C21H38O4P2F2-Si 2Pd·C4H8O, a = 15.585(2) A?, b = 12.438(2) A?, c = 17.652(2), β = 93.86(1)°, V = 3413.9(8) A?3, monoclinic, P21/n, Z = 4.
