Triflate Trimethylsilyl alcohols, elimination

N-Alkoxymethyl(trimethylsilyImethyl)amines are convenient precursors for C-unsubstituted azomethine ylides 43 since the N-alkoxymethyl(trimeth-ylsilylmethyl)amines are readily available by the reaction of N-alkylated silylmethylamines with formaldehyde in alcohol solvents (84CL1117). Treatment of the amines with trimethylsilyl triflate in acetonitrile or tetrahy-drofuran brings about the elimination of alkoxy group R O to form N-silylmethyliminium trifiates 42. The subsequent desilylation with cesium fluoride generates C-unsubstituted azomethine ylides 43 (84CL1117). Both steps of the alkoxy elimination and subsequent desilylation of 42 are induced by trifluoroacetic acid (85CPB896, 85CPB2762), tetrabutylammonium... 

Ring-opening of epoxides by P-elimination, on reaction with strong bases, such as lithium amides, or combinations of trimethylsilyl triflate with diazabicycloundecane, ° is a useful synthetic method to prepare allylic alcohols, particularly as it can be carried out enantioselectively. ... 

Vinyl triflates can be coupled efficiently to various organotin compounds. Further details of this chemistry have now appeared including efficient preparations of trimethylsilyldienes (Scheme 33).71 Two other routes to silyldienes are outlined in Scheme 34. Reduction of allenic alcohols (21) gave moderate yields of the dienyl products, although the stereoselectivity of the process leaves much to be desired. The second method, involving hydroboration of the allene (22) is much more stereoselective and enables either isomer of the final product to be obtained depending on the elimination conditions used. A key application for such dienes is in Diels-Alder reactions, where the products have vinylsilane functionality for further modification. This type of chemistry has now been explored with 2,3-bis(trimethylsilyl)buta-1,... 

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