Conjugate additions cyanotrimethylsilane

Conjugate addition. In the presence of 1 equivalent of triethylaluminum, cyanotrimethylsilane undergoes conjugate addition to a,/ -enones in high yield. The products arc converted into /J-cyano ketones by acid hydrolysis. The addition is kinetically controlled in toluene at room temperature, but thermodynamically controlled in refluxing THF (equation I). 

Conjugate Addition. Catalytic enantioselective conjugate addition of cyanotrimethylsilane to a,/3-unsaturated imides has been reported to afford 1,4-addition products in excellent yield and enantiomeric excess (eq 35). Under the catalysis of a chiral gadolinium complex, cyanotrimethylsilane can undergo facile conjugate addition to enones (eq 36) and a, 6-unsaturated... 

A-acylpyrroles (eq 37) with high enantioselectivity. The conjugate addition of cyanotrimethylsilane to, -disubstituted a,/3-unsaturated carbonyl compounds catalyzed by a chiral Sr complex provides a convenient route for the asymmetric construction of a quaternary carbon (eq 38). ... 

In the case of TMEDA, stereoselection in favor of the syn product (98 2) is enhanced over that achieved with Diiso-propylethylamine (94 6). Along with bases sueh as Triethy-lamine and ethylisopropylamine, TMEDA facilitates the preparation of cyanohydrin trimethylsilyl ethers from aldehydes and Cyanotrimethylsilane. It has been suggested that eoordination by nitrogen induces formation of an active hypervalent cyana-tion intermediate from cyanotrimethylsilane. The conjugate addition of thiols to enones has been successfully catalyzed by using TMEDA in methanol at room temperature, as exemplified by the reaction of 10-mercaptoisobomeol and 4-/-butoxycyclopentenone... 

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See also in sourсe #XX -- [ , ]

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