Highly Regio- and Stereoselective Allylation of α-Diketones via the Fluorosilicate Route
作者:Rainer Gewald、Mitsuo Kira、Hideki Sakurai
DOI:10.1055/s-1996-4151
日期:1996.1
Allylation of enolizable α-diketones with allyltrifluorosilanes in the presence of triethylamine gave the corresponding tertiary homoallyl alcohols in good yield in a highly regio- and stereospecific manner. The reaction proceeds as diallylation with allyltrifluorosilanes yielding the 1,2-diols with high diastereoselectivity. The more sterically demanding crotyl- and prenyltrifluorosilanes lead exclusively to monoallylated products with the allyl group being added γ-regioselectively. In addition, highly diastereoselective crotylation was observed in the formation of the monoallylated α-hydroxy ketones. Asymmetric α-diketones were generally allylated at the less enolized ketone group except when both diketone and allylsilane were sterically hindered.
在三乙胺存在下,使用烯丙基三氟硅烷对可烯醇化的α-二酮进行烯丙基化,得到了相应的三级同烯丙醇,产率良好,并且具有高度的区域选择性和立体选择性。该反应以双烯丙基化进行,使用烯丙基三氟硅烷生成具有高二元选择性的1,2-二醇。更具空间位阻的烯丙基-和预烯丙基三氟硅烷则专门生成单烯丙基化产物,烯丙基团以γ-区域选择性加成。此外,在形成单烯丙基化的α-羟基酮时观察到了高度的二元选择性烯丙基化。当二酮和烯丙基硅烷都受到空间位阻时,通常对不太烯醇化的酮基进行烯丙基化。