The exhaustive silylation of 5-nitro-pentan-2-one: novel processes and opportunities
                                
                                    
                                        作者:Alexander A. Tishkov、Il'ya M. Lyapkalo、Sema L. Ioffe、Yuri A. Strelenko、Vladimir A. Tartakovsky                                    
                                    
                                        DOI:10.1016/s0040-4020(01)00055-2
                                    
                                    
                                        日期:2001.3
                                    
                                    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-pent2,4-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. (C) 2001 Elsevier Science Ltd. All rights reserved.