Synthesis of vinylsilanes
A zinc-catalyzed nucleophilic substitution reaction of chlorosilanes with organomagnesium reagents affords a broad range of functionalized tetraorganosilanes under mild reaction conditions. The reaction can be performed on large scale.
K. Murakami, H. Yorimitsu, K. Oshima, J. Org. Chem., 2009, 74, 1415-1417.
Various siletanes have been used as substrates for the oxidation of carbon-silicon bonds upon exposure to aqueous fluoride and peroxide. These tetraalkylsilanes offer a combination of stability and reactivity with many practical benefits, including compatibility with silicon protecting groups and electron-rich aromatic rings.
J. D. Sunderhaus, H. Lam, G. B. Dudley, Org. Lett., 2003, 8, 4571-4573.
The nickel-catalyzed reaction of terminal alkenes with silacyclobutanes afforded the corresponding vinylsilanes in a highly regio- and stereoselective fashion. The reaction provides a facile access to vinylsilanes starting from trivial terminal alkenes as well as styrenes, 1,3-dienes, and acrylate esters.
K. Hirano, H. Yorimitsu, K. Oshima, J. Am. Chem. Soc., 2007, 129, 6094-6095.
A complex of [Ir(OMe)(cod)]2 and 4,4-di-tert-butyl-2,2-bipyridine (dtbpy) catalyzes the Z-selective, dehydrogenative silylation of terminal alkenes, but not internal alkenes, with triethylsilane or benzyldimethylsilane in THF. Yields and Z-stereoselectivity were significantly improved by 2-norbornene as sacrificial alkene. The reaction tolerates many functional groups.
B. Lu, J. R. Falck, J. Org. Chem., 2010, 75, 1701-1705.
Grubbs' first-generation Ru metathesis complex catalyses the hydrosilylation of terminal alkynes. The reaction exhibits an interesting selectivity profile that is dependent on the reaction concentration and more importantly on the silane employed.
C. S. Arico, L. R. Cox, Org. Biomol. Chem., 2004, 2, 2558-2562.
Copper(I) catalyzes a highly regioselective synthesis of branched vinylsilanes through silicon-copper additions to terminal alkynes using methanol as additive. The corresponding vinylsilanes were obtained with excellent branched to linear selectivity in good yields.
P. Wang, X.-L. Yeo, T.-P. Loh, J. Am. Chem. Soc., 2011, 133, 1254-1256.
A well-defined low-valent cobalt(I) catalyst [HCo(PMe3)4] enables a highly regio- and stereoselective hydrosilylation of internal alkynes. The reaction provides in many cases a single hydrosilylation isomer for various hydrosilanes and unsymmetrical alkynes.
A. Rivera-Hernández, B. J. Fallon, S. Ventre, C. Simon, M.-H. Tremblay, G. Gontard, E. Derat, M. Amatore, C. Aubert, M. Petit, Org. Lett., 2016, 18, 4242-4245.
A highly regioselective, catalytic hydrosilylation of terminal allenes using recyclable gold nanoparticles as catalyst does not require any external ligands or additives. The hydrosilane addition takes place on the more substituted double bond, which is attributed to steric and electronic factors.
M. Kidonakis, M. Stratakis, Org. Lett., 2015, 17, 4538-4541.
A one-pot regioselective allene hydrosilylation/Pd(0)-catalyzed cross-coupling protocol affords functionalized 1,1-disubstituted alkenes with excellent regiocontrol. The regioselectivity of this hydroarylation is primarily governed by N-heterocyclic carbene (NHC) ligand identity in the hydrosilylation step and is preserved in the subsequent cross-coupling reaction.
Z. D. Miller, J. Montgomery, Org. Lett., 2014, 16, 5486-5489.
In regioselective methods for allene hydrosilylation, alkenylsilanes are produced via nickel catalysis with larger N-heterocyclic carbene (NHC) ligands, whereas allylsilanes are produced via palladium catalysis with smaller NHC ligands. These complementary methods allow either regioisomeric product to be obtained with exceptional regiocontrol.
Z. D. Miller, W. Li, T. R. Belderrain, J. Montgomery, J. Am. Chem. Soc., 2013, 135, 15282-15285.
A silyl-Heck reaction allows the preparation of vinyl silyl ethers and disiloxanes rom aryl-substituted alkenes and related substrates using a commercially available catalyst system and mild conditions. This work represents a highly practical means of accessing diverse classes of vinyl silyl ether substrates in an efficient and direct manner with complete regiomeric and geometric selectivity.
S. E. S. Martin, D. A. Watson, J. Am. Chem. Soc., 2013, 135, 13330-13333.
Palladium catalyzes a highly regio- and stereoselective hydrosilylation applicable to a broad range of electron-deficient alkynes. The resulting α-silylalkenes can be further transformated using particularly Hiyama coupling and stereoinverting iododesilylation followed by Suzuki-Miyaura coupling, which enables stereodivergent syntheses of α-arylenoates.
Y. Sumida, T. Kato, S. Yoshida, T. Hosoya, Org. Lett., 2012, 14, 1552-1555.
A highly regio- and stereoselective palladium-catalyzed synthesis of various 2-silylallylboronates from allenes and 2-(dimethylphenylsilanyl)-4,4,5,5-tetramethyl[1,3,2]dioxaborolane afforded the corresponding silaboration products in moderate to excellent yields. In the absence of an organic iodide, the silaboration gives products having completely different regiochemistry. In the presence of an aldehyde, the silaboration reaction afforded homoallylic alcohols in one pot in good to excellent yields, with exceedingly high syn selectivity.
K.-J. Chang, D. K. Rayabarapu, F.-Y. Yang, C.-H. Cheng, J. Am. Chem. Soc., 2005,127, 126-131.
Low catalyst loadings of (IPr)Pt(allyl ether) display enhanced activity and regioselectivity for the hydrosilylation of terminal and internal alkynes. Reactions lead to exquisite regioselectivity in favor of the cis-addition product on the less hindered terminus of terminal and internal alkynes.
G. Berthon-Gelloz, J.-M. Schumers, G. De Bo, I. E. Markó, J. Org. Chem., 2008, 73, 4190-4197.
The use of a catalytic amount of PtCl2 enables the conversion of α-hydroxypropargylsilanes to (Z)-silylenones through a highly selective silicon migration via alkyne activation. The complementary (E)-silylenones are accessed by a regioselective hydrosilylation of the ynone precursor.
D. A. Rooke, E. M. Ferreira, J. Am. Chem. Soc., 2010, 132, 11926-11928.
A facile synthesis of 1-silyl-substituted 1,3-butadienes is based on a [RuHCl(CO)(PCy3)2]-catalyzed silylative coupling of terminal (E)-1,3-dienes with vinylsilanes. The reaction provides (E,E)-dienylsilanes in a highly stereoselective fashion with elimination of ethylene as a single byproduct.
J. Szudkowska-Frątczak, B. Marciniec, G. Hreczycho, M. Kubicki, P. Pawluć, Org. Lett., 2015, 17, 2366-2369.
The silicon nucleophile generated by copper(I)-catalyzed Si-B bond activation allows several γ-selective propargylic substitutions. Chloride as a leaving groups is superior in linear substrates, and the phosphate group produces superb γ-selectivity in α-branched propargylic systems, and enantioenriched substrates react with excellent central-to-axial chirality transfer.
D. J. Vyas, C. K. Hazra, M. Oestreich, Org. Lett., 2011, 13, 4462-4465.
A Rh-catalyzed coupling reaction between propargylic carbonates and a silylboronate affords allenylsilanes in high yields. The reaction tolerates various functional groups and proceeds with excellent chirality transfer.
H. Ohmiya, H. Ito, M. Sawamura, Org. Lett., 2009, 11, 5618-5620.
Copper(I)-catalyzed propargylic substitution of linear precursors with one equivalent of (Me2PhSi)2Zn predominantly yields the γ isomer independent of the propargylic leaving group. The formed allenylic silane can regioselectively react with a second equivalent of (Me2PhSi)2Zn to give a bifunctional building block with allylic and vinylic silicon groups. The propargylic displacement occurs quantitatively prior to the addition step.
C. K. Hazra, M. Oestreich, Org. Lett., 2012, 14, 4010-4013.
A copper-catalzed functionalization of propiolate esters with various Grignard reagents in presence of trimethylsilyl trifluoromethanesulfonate enables the synthesis of substituted E-vinyl silanes in good yields and excellent diastereoselectivities via a catalytic carbocupration-silicon group migration sequence.
A. J. Mueller Hendrix, M. P. Jennings, Org. Lett., 2010, 12, 2750-2753.
A new approach to 2-(arylmethyl)aldehydes begins with a silylformylation reaction of terminal acetylenes with aryl- or heteroarylsilanes, followed by treatment of the products with TBAF to induce a 1,2-anionotropic rearrangement of the aryl group.
L. A. Aronica, P. Raffa, A. M. Caporusso, P. Salvadori, J. Org. Chem., 2003, 5, 9292-9298.
In the presence of Pd(0) and a phosphine, a hydrosilylation of 1,3-enynes with Me2SiHCl yields dienylsilanes with (E)-configuration and with the silicon group added to the internal alkyne carbon atom. Subsequent hydrolysis gives silanols, that serve as precursors to conjugated dienes with different substitution patterns.
H. Zhou, C. Moberg, Org. Lett., 2013, 15, 1444-1447.
Supported gold nanoparticles on metal oxides catalyze a cis-selective disilylation of terminal alkynes with 1,2-disilanes in good isolated yields. The reaction probably proceeds through oxidative insertion of the σ Si-Si bond on gold followed by 1,2-addition to the alkyne.
C. Gryparis, M. Kidonakis, M. Stratakis, Org. Lett., 2013, 15, 6038-6041.
The presence of supported gold nanoparticles enables gold-catalyzed silaboration of terminal alkynes with PhMe2SiBpin. The reaction proceeds at ambient conditions in very good yields with a regioselectivity opposite to that observed in the presence of Pd or Pt catalysts. The abnormal regioselectivity is attributed to steric factors imposed by the Au nanoparticle during the 1,2-addition of silylborane to the alkyne.
C. Gryparis, M. Stratakis, Org. Lett., 2014, 16, 1430-1433.
An efficient Pd-catalyzed addition of boronic acids to silylacetylenes provides β,β-disubstituted (E)- or (Z)-alkenylsilanes in good yields with excellent regio- and stereoselectivity under mild reaction conditions. Moreover, a sequential Pd-catalyzed boron addition/N-halosuccinimide-mediated halodesilylation reaction results in a stereodivergent approach to β,β-disubstituted alkenyl halides as versatile synthetic intermediates.
W. Kong, C. Che, J. Wu, L. Ma, G. Zhu, J. Org. Chem., 2014, 79, 5799-5805.
A new cyclopropenation reaction, which involves Cα-Si bond insertion of alkylidene carbenes derived from α-silyl ketones, features excellent selectivity for insertion into Cα-Si bonds rather than insertion into Cγ-H bonds or addition to γ,δ-double or -triple bonds. The selectivity trend clearly indicates that the α-oxygen in the tether significantly promotes Cγ-H insertion.
J. Li, C. Sun, D. Lee, J. Am. Chem. Soc., 2010, 132, 6640-6641.