Trimethylsilyloxycyclopropane

For example, Nakamura and Kuwajima [15] have described 1-alkoxy-l-trimethylsilyloxycyclopropanes (15) -prepared by reductive silylation of alkoxy 3-chloropropanoates-, which react with aliphatic aldehydes, but not with ketones, in the presence of one equivalent of TiCl4 to give good yields of y-lactones 17 through the acyclic derivative ethyl 4-hydroxybutanoate (16) (Scheme 5.10). With aromatic aldehydes and their acetals the reaction leads directly to acyclic 1,4-D derivatives. 

The most recent source of these iminium ion precursors is the amide derived from 3-chloropropionyl chloride. Using the procedure reported by Ruhlmann for the preparation of 1-methoxy-l-trimethylsilyloxycyclopropane, Wasserman and Dion " converted the piperidide (58) to the 1-piperidino-l-trimethylsilyloxycyclopropane (59) by treatment with sodium metal in dry ether at 0°C. This reaction, which takes place smoothly and in high yield, serves as a short, inexpensive way to form the stable cyclopropanone equivalent. Further reaction of the silyl derivative (59) with tetrabutylam-monium fluoride in THF yields the corresponding carbinol amine (60). 

Ring expansion of trimethylsilyloxycyclopropanes, using the reaction between 1-trimethylsilyloxycyclohex-l-ene and CH2I2/Et2Zn. FeCl3-catalysed opening gives 3-chlorocycloheptanone, and thence cyclohept-2-enone. 

Insertion into C—H bonds is also a reaction type common to nitrene chemistry. This is observed in the formation of the cyclopropylamine 615 from reaction with 1-ethoxy-l-trimethylsilyloxycyclopropane. Details have been reported of the use that can be made of the addition of the same nitrene to the chiral silyloxyalkene 616. This leads to an asymmetric synthesis of the amine 6YT. Insertion of a nitrene into C—H bonds is also reported for the photodecomposition of/7-trimethylsilylbenzoyl azide in hydrocarbons Reports have been made concerning the non-specificity of this particular nitrene. Apprently, some control can be exercised on its reactivity by using a micellar system. Under conditions of this type, using N, A-dimethyloctylammonium propionate as the micellar material, only the formamidine 618 is obtained ... 

Cyclopropylamine Formation. The cyclopropylation of a variety of amines is easily accomplished by reductive amination with 1-ethoxy-1-trimethylsilyloxycyclopropane (eq 23). This mild and general one-pot cyclopropylation method is useful in medicinal and synthetic organic chemistry to enhance the biological activity of compounds bearing amine functions. ... 

The palladium-catalysed oxyamination of olefins is well known, and it has now been found that, by the use of chiral reagents, asymmetry can be induced in the amination step and that optically active tertiary amino-alcohols result. 1-Piperidino-l-trimethylsilyloxycyclopropane and the corresponding 1-hydroxy-compound have been prepared and examined for their utility as cyclopropanone equivalents. ... 

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