Dodecacarbonyltetrarhodium-Dimethyl(phenyl)silane-Carbon Monoxide

Rh4(CO)12-HSiMe2Ph-CO
(Rh4(CO)12)

[19584-30-6]  · C12O12Rh4  · Dodecacarbonyltetrarhodium-Dimethyl(phenyl)silane-Carbon Monoxide  · (MW 747.76) (HSiMe2Ph)

[766-77-8]  · C8H12Si  · Dodecacarbonyltetrarhodium-Dimethyl(phenyl)silane-Carbon Monoxide  · (MW 136.29) (CO)

[630-08-0]  · CO  · Dodecacarbonyltetrarhodium-Dimethyl(phenyl)silane-Carbon Monoxide  · (MW 28.01)

(silylformylation of alkynes,1 aldehydes,8 and oxiranes;11 siloxymethylenation of enamines10)

Physical Data: Rh4(CO)12: decomposes to Rh6(CO)16 at 130-140 °C under N2. HSiMe2Ph: bp 157 °C/744 mmHg; nD20 1.4995; d420 0.889 g cm-3.

Solubility: Rh4(CO)12: readily sol CH2Cl2, CHCl3; sol THF, acetone, toluene, pentane; less sol MeOH, cyclohexane.

Form Supplied in: Rh4(CO)12: dark red when crystalline; orange when powdered. HSiMe2Ph: colorless oil.

Purification: Rh4(CO)12: a typical impurity is a trace amount of Rh6(CO)16. A Rh6(CO)16-free product can be obtained by extraction, under CO with pentane, followed by crystallization at -70 °C, filtration at this temperature, and drying in a stream of CO.

Handling, Storage, and Precautions: Rh4(CO)12: stable in air, although on prolonged standing decomposition occurs; best stored under a CO atmosphere.

Silylformylation.

Silylformylation of alkynes with Dimethyl(phenyl)silane and Carbon Monoxide leading to b-silylacrylaldehydes is catalyzed by Dodecacarbonyltetrarhodium/Triethylamine (eq 1).1 Co2Rh2(CO)122 and Dirhodium(II) Tetrakis(perfluorobutyrate)3 are also effective for the silylformylation of alkynes. The reaction has been applied to the formation of b-lactones from propargyl alcohols (eq 2).4 The products in the reaction of propargyl amines depend on the nature of substituents on nitrogen (eqs 3 and 4).5 The Rh4(CO)12/HSiMe2Ph/CO combination acts on a diyne to afford a bicyclic ketone (eq 5).6 Rh-catalyzed silylformylation of alkynes has also been applied to the synthesis of pyrrolizidine alkaloids.7

Di-m-chlorobis(1,5-cyclooctadiene)dirhodium(I) is also an active catalyst for silylformylation of aldehydes, leading to a-siloxy aldehydes under mild reaction conditions (eq 6).8 Hydrosilanes such as HSiEt3 and HSiPh3 are not effective reagents for Rh-catalyzed silylformylation of aldehydes and HSiEt3 was recovered intact.

[RhCl(CO)2]2/HSiEt2Me/CO.

This similar reaction system has been found to be effective for the incorporation of CO into the a-carbon atom of enamines to give a-(siloxymethylene)amines, which can be easily converted into a-siloxy ketones by hydrolysis (eq 7).9 The system has also been utilized for the incorporation of CO into N,N-acetals (eq 8).10 Ring-opening silylformylation of oxiranes is also catalyzed by Tetracarbonyl(di-m-chloro)dirhodium (eq 9).11 The use of HSiMe2Ph as the hydrosilane gives a higher product yield than with HSiEt2Me.

Related Reagents.

Carbon Monoxide; Octacarbonyldicobalt-Diethyl(methyl)silane-Carbon Monoxide; Tricarbonylchloroiridium-Diethyl(methyl)silane-Carbon Monoxide.


1. Matsuda, I.; Ogiso, A.; Sato, S.; Izumi, Y. JACS 1989, 111, 2332.
2. Ojima, I.; Ingallina, P.; Donovan, R. J.; Clos, N. OM 1991, 10, 38.
3. Doyle, M. P.; Shanklin, M. S. OM 1993, 12, 11.
4. Matsuda, I.; Ogiso, A.; Sato, S. JACS 1990, 112, 6120.
5. (a) Matsuda, I.; Sakakibara, J.; Nagashima, H. TL 1991, 32, 7431. (b) Matsuda, I.; Sakakibara, J.; Inoue, H.; Nagashima, H. TL 1992, 33, 5799.
6. Ojima, I.; Donovan, R. J.; Shay, W. R. JACS 1992, 114, 6580.
7. Eguchi, M.; Zeng, Q.; Korda, A.; Ojima, I. TL 1993, 34, 915.
8. Wright, M. E.; Cochran, B. B. JACS 1993, 115, 2059.
9. Ikeda, S.; Chatani, N.; Kajikawa, Y.; Ohe, K.; Murai, S. JOC 1992, 57, 2.
10. Ikeda, S.; Chatani, N.; Murai, S. OM 1992, 11, 3494.
11. Fukumoto, Y.; Chatani, N.; Murai, S. JOC 1993, 58, 4187.

Naoto Chatani & Shinji Murai

Osaka University, Japan



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