18146-03-7Relevant academic research and scientific papers
Iron Catalyzed Hydroformylation of Alkenes under Mild Conditions: Evidence of an Fe(II) Catalyzed Process
Pandey, Swechchha,Raj, K. Vipin,Shinde, Dinesh R.,Vanka, Kumar,Kashyap, Varchaswal,Kurungot, Sreekumar,Vinod,Chikkali, Samir H.
supporting information, p. 4430 - 4439 (2018/04/05)
Earth abundant, first row transition metals offer a cheap and sustainable alternative to the rare and precious metals. However, utilization of first row metals in catalysis requires harsh reaction conditions, suffers from limited activity, and fails to tolerate functional groups. Reported here is a highly efficient iron catalyzed hydroformylation of alkenes under mild conditions. This protocol operates at 10-30 bar syngas pressure below 100 °C, utilizes readily available ligands, and applies to an array of olefins. Thus, the iron precursor [HFe(CO)4]-[Ph3PNPPh3]+ (1) in the presence of triphenyl phosphine catalyzes the hydroformylation of 1-hexene (S2), 1-octene (S1), 1-decene (S3), 1-dodecene (S4), 1-octadecene (S5), trimethoxy(vinyl)silane (S6), trimethyl(vinyl)silane (S7), cardanol (S8), 2,3-dihydrofuran (S9), allyl malonic acid (S10), styrene (S11), 4-methylstyrene (S12), 4-iBu-styrene (S13), 4-tBu-styrene (S14), 4-methoxy styrene (S15), 4-acetoxy styrene (S16), 4-bromo styrene (S17), 4-chloro styrene (S18), 4-vinylbenzonitrile (S19), 4-vinylbenzoic acid (S20), and allyl benzene (S21) to corresponding aldehydes in good to excellent yields. Both electron donating and electron withdrawing substituents could be tolerated and excellent conversions were obtained for S11-S20. Remarkably, the addition of 1 mol % acetic acid promotes the reaction to completion within 16-24 h. Detailed mechanistic investigations revealed in situ formation of an iron-dihydride complex [H2Fe(CO)2(PPh3)2] (A) as an active catalytic species. This finding was further supported by cyclic voltammetry investigations and intermediacy of an Fe(0)-Fe(II) species was established. Combined experimental and computational investigations support the existence of an iron-dihydride as the catalyst resting state, which then follows a Fe(II) based catalytic cycle to produce aldehyde.
Process for making camptothecin derivatives
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Page 6, (2008/06/13)
A process for synthesizing highly lipophilic derivatives of camptothecin. The process includes reacting dissolved, underivatized camptothecin with an aldehyde in a modified Minisci-type alkylation reaction to produce 7-substituted derivatives of camptothecin.
The Regioselectivite Hydroformylation of Vinylsilanes. A Remarkable Difference in the Selectivity and Reactivity of Cobalt, Rhodium, and Iridium Catalysts
Crudden, Cathleen M.,Alper, Howard
, p. 3091 - 3097 (2007/10/02)
The zwitterionic rhodium complex, Rh(COD)BPh4, produces 2-(trimethylsilyl)propanal selectively in the hydroformylation of trimethylvinylsilane under quite mild conditions .Excess hydrogen is crucial for obtaining the branched aldehyde as the major product (B:L = 70:30).This is the first reported example of an α-selective hydroformylation of vinylsilanes.The potentially useful α-silyl aldehydes are difficult to prepare and isolate by other means, but using this procedure they can be obtained in one step from commercially available vinyltrimethylsilane, albeit in low isolated yields (20-30percent).The addition of as little as 2 equiv of PPh3 causes a complete shift in the selectivity yielding the linear isomer as the major product in the hydroformylation of vinyltriethylsilane (B:L = 7:93).The isolated yield increases from 30percent to 91percent after only 1.5 h.Iridium catalysts yielded the linear aldehydes (3-(trialkylsilyl)propanal) with excellent regioselectivities (90-100percent) without the addition of any phosphine.A competing reaction is hydrogenation of the starting material.This can be suppressed by increasing the amount of CO in the gas mixture (CO:H2 = 7:1).Of those complexes examined, hydrated IrCl3 (after preactivation at 160 deg C) gave the best selectivity for the linear isomer (98-100percent).The cationic complex, (+)BF4, also gave the linear aldehyde predominantly (95-97percent) in 75-80percent yields.Although most of the cobalt complexes tested were unreactive, the cationic cobalt cluster 6-C6H6)3(μ3-CO)2>BPh4 was the most active catalyst for the hydroformylation of vinyltriethylsilane.At 100 deg C, this complex completed six turnovers per minute, yielding the linear silyl aldehyde as the major product (B:L = 24:76).
Stereoselective Synthesis of (E)- and (Z)-2-Alkenyltrimethylsilanes from 1,2-Epoxy-1,3-bis(trimethylsilyl)propane
Shimizu, Nobujiro,Imazu, Sachiko,Shibata, Fumihiro,Tsuno, Yuho
, p. 1122 - 1128 (2007/10/02)
Stereoselective synthesis of various (E)- and (Z)-2-alkenyltrimethylsilanes (RCH=CHCH2SiMe3; R=Me, Et, n-Bu, i-Pr, c-hexyl, t-butyl, and phenyl) has been accomplished by a reaction of 1,2-epoxy-1,3-bis(trimethylsilyl)propane with Grignard reagents (RMgX) followed by subsequent Peterson olefination reactions of resulting 1,2-bis(trimethylsilyl)-3-alkanols ; the acid (BF3OEt2 or HClO4)-catalyzed olefination yields the (E)-isomer, while the base (KH or NaH)-induced olefination yields the (Z)-isomer in more than 95 percent stereochemical purity in most cases.
Hydroformylation of alkenes having organosilicon substituents
Takeuchi, Ryo,Sato, Nobuhiro
, p. 1 - 10 (2007/10/02)
The hydroformylation of vinyltrimethylsilane catalyzed by transition metal complexes has been studied.Rh catalysts showed high activity with low regioselectivity.Addition of large excess of triphenylphosphine improved the regioselectivity to normal aldehyde.In contrast, a Co and a Pt catalyst gave exclusively n-aldehyde.Vinyltrimethoxysilane is also hydroformylated by transition metal catalysts.The factors of regioselectivity are discussed.
REGIO- AND STEREOSELECTIVE SYNTHESIS OF ALLYLTRIMETHYLSILANES VIA KRIEF-REICH ELIMINATION IN β-SELENO-γ-SILYL ALCOHOLS
Sarkar, Tarun K.,Ghosh, Sunil K.,Satapathi, Tushar K.
, p. 1885 - 1898 (2007/10/02)
The synthesis of (E)-allyltrimethylsilanes by regio- and stereocontrolled pathways is described based on the preference for Krief-Reich elimination over silicon-controlled rearrangement in β-seleno-γ-silyl alcohols, readily available from α-selenoaldehydes, 10 - 12.Usefulness of this protocol for the introduction of the allylsilane function α to the carbonyl group in cycloalkanones as well as for the preparation of unsymmetrically substituted allylsilanes is also reported.
γ-Silicon Stabilization of Carbonium Ions in Solvolysis. 2. Solvolysis of 4-(Trimethylsilyl)-2-butyl p-Bromobenzenesulfonates
Shiner, V. J.,Ensinger, Mark W.,Rutkowske, Randy D.
, p. 804 - 809 (2007/10/02)
The solvolysis of 4-(trimethylsilyl)-2-butyl p-bromobenzenesulfonate produces racemic substitution products and a minor amount of methylcyclopropane at a rate which is several-fold faster than the solvolysis of its carbon analogue; polarimetric and conductometric rates are not significantly different.Added LiClO4, KOH, KOBs, and LiOBs produced normal salt effects on the polarimetric rate; b values varied from 0.2 to 130, depending on the nature of the salt and solvent.The deuterium isotope rate effects vary somewhat with solvent as follows: α-d, 1.12-1.15; β-d3, 1.115-1.16; β-d2, 0.975-1.07.It is concluded that the γ-silyl group promotes the solvolysis and stabilizes the intermediate carbonium ion.The "W" and "sickle" conformations of the transition states for the formation and/or reaction of the carbonium ion intermediate have approximately equal energies.
SILICON-CONTROLLED REARRANGEMENT VERSUS KRIEF-REICH REACTION IN β-SELENO-γ-SILYL ALCOHOLS : A NEW STEREOSELECTIVE SYNTHESIS OF TERMINALLY-SUBSTITUTED ALLYLSILANES
Sarkar, Tarun K.,Ghosh, Sunil K.
, p. 2061 - 2064 (2007/10/02)
A new and efficient route to terminally-substituted (E)-allylsilanes is described based on the preference for Krief-Reich elimination in several β-seleno-γ-silyl alcohols, readily available by diastereoselective addition of various Grignard reagents or aldol reaction on 2-(phenylseleno)-3-(trimethylsilyl)propanal(9).
