在Mitsunobu 反應中,用鹵原子取代羥基生成鹵代物也有報導,但其應用還不多見。Falck 等報導了通過Mitsunobu 過程合成一系列的鹵代烴,除了氟代的產率不高以外,氯代,溴代和碘代的產率都不錯。
【Manna, S; Falck, J.R. Synth. Commun. 1985, 15, 663】
Joulle 等報導脯胺酸衍生物在經過Mitsunobu過程后得到手性翻轉的碘代產物。反應首先是生成一個甲醚中間體,然后在三苯膦的作用下發生碘代,同時手性翻轉。
To a flame-driedround-bottomed flask eguipped with a magnetic stir bar and an addition funnelunder N2 was added N-Boc-trans-4-hydroxy-L-proline methyl ester(19.29 g, 0.079 mol), triphenylphosphine (24.78 g, 0.094 mol) and anhydrous THF(2755 mL). The solution was cooled to 0oC. Diethyl azodicarboxylate(DEAD, 14.9 mL, 0.094 mol) in anhydrous THF (15 mL) was added dropwise,followed by the addition of methyl iodide (5.88 mL, 0.094 mol). Upon additionof MeI, the solution turned from dark brown to bright yellow. The reactionmixture was allowed to warm to ambient temperature and stirred for 10 h. Thesolvent was removed under reduced pressure and the crude oil was purified bycolumn chromatograghy, eluting with 5% EA/PE to afford the desired product as awhite solid (26.22 g, 93.8%).
【Schumacher, K. K;Jiang, J; Joulle, M. M. Tetrahedron: Asymm. 1998, 9, 47】
本文非原創內容,版權歸原作者所有。
?