The exhaustive silylation of 5-nitro-pentan-2-one: novel processes and opportunities

Treatment of 5-nitro-pentan-2-one (1) with Me3SiOTf/Et3N leads to initial silylation of the C(O)Me-group to give regioisomeric silyl enol ethers 2a and 2b followed by double silylation of the NO2-group furnishing a mixture of N,N-bis(silyloxy)enamine 4a and enoxime TMS ether 6. Employment of a large excess of Me3SiOTf/Et3N triggers a cascade of eliminations and silylations to give a mixture of (E)-4-trimethylsilyloxy-2-trimethylsilyl-pent-2,4-dienenitrile (8) and 3-oxo-1-(1,1,1-trimethylsilyl)-1-cyclobutanecarbonitrile (9). The use of Me3SiCl/DBU changes the selectivity of silylation of 1 to give silyl nitronate 2c.