Silicon-Controlled Allylation of 1,3-Dioxo Compounds by Use of Allyltrimethylsilane and Ceric Ammonium Nitrate

Abstract

A new method was developed for allylation of 1,3-diketones, ß-keto esters, and malonates. Treatment of those 1,3-dioxo compounds with allyltrimethylsilane (1.3 equiv) in the presence of ceric ammonium nitrate (2.1 equiv) in methanol at room temperature often gave the mono-Callylated products in good to excellent yields (74-98%). These reactions, involving /3-carboradical and /3-carbocationic intermediates, were controlled by a silyl group. Replacement of ceric ammonium nitrate and methanol with manganese(III) acetate (2.4 equiv) and acetic acid afforded siliconcontaining dihydrofurans in high yields at 80 °C.

Allylsilanes in Organic Synthesis − Recent Developments

“…Ketones can also be added to allylsilanes through a radical pathway, but under oxidative conditions. [97] When using MnO 2 as oxidant, a purely radical process operated with hydrogen-atom transfer. The reaction of the ketone with MnO 2 (used in large excess) is believed to generate a radical centre α to the carbonyl group, which can then add at the terminal sp 2 -carbon atom of allylsilane 171 to form a β-silyl carboradical intermediate (Scheme 48).…”

Cycloadditions of allylsilances. Part 10. Stereoselective Construction of Ring Systems by Cycloaddition Reactions of allyltriisopropylsilance

“…A further example for the construction of four-membered ring heterocycles by [2+21 cycloaddition of allyltriisopropylsilane l b has recently been reported by Uyehara [34]. The reaction of l b with N-acylaldimines The oxidative addition of 1,3-dicarbonyI compounds with allyltriisopropylsilane as described by Hwu afforded dihydrofurans (Scheme 21, Table 7) [36]. These reactions are initiated by one-electron oxidizing agents, e.g.…”

Silicon-controlled Carbon-Carbon Bond Formation and Cyclization between Carbonyl Compounds and Allyltrimethylsilane

“…Intramolecular cyclization often takes place in 1,3-diketones and ␤-keto esters that bear a ␥carboradical moiety (such as 19) to give dihydrofurans. 9,19 Nevertheless, we did not obtain any dihydrofuran derivatives upon treatment of 1,3-indandione (11) with allyltrimethylsilane and Mn(OAc) 3 · 2H 2 O. We believe that the angle strain existing in the fivemembered ring of the intermediate 19 may provide an unfavorable environment for the formation of an extra dihydrofuran ring fused to the indandione nucleus.…”

“…In the course of studying silicon-controlled organic reactions, [7][8][9][10][11][12][13][14][15] we investigated the synthetic applicability of addition of ketones to allylsilanes by use of ceric ammonium nitrate (CAN), manganese(III) acetate or a mixture of CAN and manganese(III) acetate along with cupric acetate. Manipulation of the reaction conditions would enable us to accomplish monoallylation, diallylation, allylation followed by ring formation, and allylation-cyclization-elimination of carbonyl compounds.…”