ORGN 94 |
| The [2,3]-sigmatropic rearrangement of a-alkoxylithiums provides useful routes to a variety of homoallylic alcohols. Still showed that the rearrangement may be initiated by tin-lithium exchange of -a-alkoxy stannane. A similar carbanionic [2,3]-rearrangement is also feasible on allylic sulfides and amine counterparts, however, the analogous reaction of a-aminoorganostannanes is rare. Years ago our group reported [2,3]-aza-Wittig rearrangement of N-alkyl-2-lithio pyrrolidine and three examples of rearrangements of nitrogen ylides. We have now investigated the possibility of using this reaction to generate two contiguous stereocenters. Stannylpiperidine 1 and stannylpyrrolidine 4 were converted into quaternary salts 2 and 5, which X-ray data showed to be a single diastereomer in quantitative yield. Transmetalation of 2 and 5 with MeLi or BuLi at low temperature affords 3 and 6, respectively, as single diastereomers.
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Asymmetric Reactions and Syntheses, Physical Organic Chemistry, Combinatorial Chemistry, Total Synthesis
8:00 PM-10:00 PM, Sunday, 26 March 2006 Georgia World Congress Center -- Ex. Hall B4, Poster
Division of Organic Chemistry |
