Amines potassium hexamethyldisilazide

NPf) protected amine. The final ring formation was carried out by deprotonation of the benzylic methyl with potassium hexamethyldisilazide (KHMDS) which then added to the methyl ester to provide ketone 316. This compound was then carried on through a series of transformations to provide a common intermediate for every member of the FR900482 family. 

A number of interesting reactions have been carried out on ring systems of which the azepine ring is just one example of a number of cyclic amines. For example, treatment of (70) with potassium hexamethyldisilazide in THF at —78°C followed by trisyl azide gives a 65% yield of the /ru/ii-azide (71) <92TL6859>. A phenylseleno derivative is formed in 78% yield when trisyl azide is replaced by phenylselenylchloride. 

Potassium hexamethyldisilazide, KHMDS, has been used successfully in the past for a-deprotonation of sulfoxides. Aiming to probe the nature of the transition state in the reaction of a-metalated (i )-methyl //-tolyl sulfoxide with A -(benzylidene) aniline under kinetic conditions, the effect of the choice of the bases for the a-deprotonation on the reactivity and diastereoselectivity was studied, using LDA, LHMDS, NaHMDS, and KHMDS. Best yields anddiastereoselectivities (90%, 84 16) were achieved with LDA, whereas LHMDS showed diminished reactivity (50%) without a loss of diastereoselectivity (87 13). Improved yields and lower diastereoselectivities were recorded in reactions mediated by NaHMDS and KHMDS, providing the amine in 60% (dr 81 19) and 77% (dr 69 31) yields and diastereoselectivities, respectively (eq 64). 

Lithium hexamethyldisilazide, 165 Potassium permanganate, 258 Trialkylaluminums, 21 Tris[2-(2-methoxyethoxy)ethyl]amine, 336... 

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