REACTIONS OF (CO)5MNSI(CH3)3 WITH ORGANIC CARBONYL-COMPOUNDS
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Reactions of (CO) 5 MnSi(CH 3 ) 3 (1) with organic carbonyl compounds have been investigated as a means of developing new metal-carbon bond-forming reactions. Benzaldehyde and 1 react over 2 weeks at 5 C to give the silyloxyalkyl complex (CO) 5 MnCH(C 6 H 5 )OSi(CH 3 )3 (2) in 65-90% yield, depending upon conditions. Complex 2 undergoes rapid homolysis at 80 C to [(CO) 5 Mn]2 and the diastereomeric pinacol ethers [-CH(C 6 H 5 )OSi(CH 3 )3]2 (3a, 3b). Reactions of 1 with p-methoxybenzaldehyde and p-(dimethylamino) benzaldehyde are much faster but yield organometallic products which are much less stable toward homolysis. Compound 1 and butyraldehyde react to yield (CO) 5 MnH and the E and Z isomers (3:2 ratio) of butyraldehyde trimethylsilyl enol ether (8, 9). The isolation of (CO) 5 MnCOCH(n-C3H7)OSi(CH 3 )3 (14) when this reaction is conducted under 10 atm of CO provides good evidence for the intermediacy, of (CO) 5 MnCH(n- C3H7)OSi(CH 3 )3. Acetone, cyclohexanone, and 2-methylcyclohexanone similarly react with 1 to yield (CO) 5 MnH and trimethylsilyl enol ethers. In the latter case, a mixture of regioisomers is formed which equilibrate due to the (CO) 5 MnH present. These reactions are suggested to proceed via rate-determining formation of ion pairs (CO) 5 Mn-+CR(R')OSi(CH 3 )3. The thermodynamics and relevance of these reactions to catalytic hydrosilylation processes are discussed. 1981, American Chemical Society. All rights reserved.
