Enol ethers germyl

Scheme 12 Perfluoroalkylation of ketones via germyl enol ethers...

Germyl enol ethers react with perfluoroalkyl iodides under Et3B initiation to give a-pcrfluoroalkyl ketones. The intermediate radical adduct decomposes readily via /1-elimination and provides the a-perfluoroalkyl ketone and a trialkylgermanyl radical as a chain carrier (Scheme 12) [32]. 

The DFT study of the 3 + 2-cycloaddition between ketene and TV-silyl-, IV-germyl-, and TV-stannyl-imines shows that the TV-germylimine reaction is a two-step process the TV-stannylimine reaction is a competition between two- and three-step processes whereas the TV-silyl process follows a three-step process44 A new and convenient synthesis of functionalized furans and benzofurans based on 3 + 2-cycloaddition/oxidation has been reported. The cyclization of cyclic 1,3-bis-silyl enol ethers (48) with l-chloro-2,2-dimethoxyethane (49), via a dianion, produced 5,6-bicyclic 2-alkylidenetetrahydrofurans (50), which are readily oxidized with DDQ to 2,3-unsubstituted benzofurans (51) (Scheme 13)45 The Evans bis(oxazoline)-Cu(II) complex catalyses the asymmetric 1,3-dipolar cycloaddition of a -hydroxyenones with nitrones to produce isoxazolidines.46 The... 

This chapter is concerned with the reactions of enol ethers with carbonyl compounds as illustrated in Scheme 1. The enol ethers considered include alkyl, silyl, germyl and stannyl ethers, and to a small extent enol esters. The carbonyl compounds encompass aldehydes, ketones, esters and their functional equivalents. Overall, the reaction depicted in Scheme 1 is similar to the classical aldol and related condensations discussed in Part 1 of this volume. However, in contrast to the basic conditions inherent in... 

Enol germyl ethers are known to equilibrate slowly with the C-isomers at room temperature. They can be prepared by the reaction of lithium enolates of ketones with chlorotrimethylgermane as a mixture of the O- and C-germyl isomers (e.g. 89). ... 

Enol germyl ethers are expected to be more stable than the corresponding enol stannyl ethers, but more reactive than the enol silyl ethers. A recent study shows that enol germyl ethers derived from a number of ketones e.g. 162) condense with benzaldehyde at -78 to -40 C without the need for a catalyst. However, the yield of the product (163) appears to be improved by the addition of BF.vOEt2. Interestingly, the presence of lithium halide also affects the reaction (Scheme 54). 

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