Silacyclopropane synthesis

Silacyclopropane, 1,1 -difluorotetramethyl-decomposition, 1, 587 Silacyclopropanes, I, 575-581 ring expansion, I, 587 Silacyclopropenes, I, 583-587 minimum energy geometry, I, 587 ring expansion, 1, 587 7-Siladispiro[2.0.2.1 jheptane synthesis, I, 576... 

Compound 1 did not react with unstimned internal olefins such as tetramethylethylene, /ra s-3-hexene, tram-stilbene, cyclooctene, cyclohexene, or cyclopentene. But imposing strain to the olefinic moiety resulted in a clean silylene transfer to the double bond Norbomene formed with 1 the tricyclic silacyclopropane 6. Whereas 2 did not add to the double bond of 7, methylene cyclopropane 8 could be transformed into spiro[2.2]pentane 9 by reaction with 1. Addition of 2 to bicyclopropylidene allowed the convenient synthesis of dispiro[2.0.2.1]heptane 10 in a quantitative manner. 

Cyclohexene silacyclopropane 47 undergoes silver-catalyzed silylene transfer, acting as an efficient method for silacyclopropane 48 synthesis (Equation 5) <2004JOC4007>. Kinetic studies of the transfer reaction suggested a possible mechanism for silver-mediated silylene transfer with a kinetic order of one for 47 <2004JA9993>. 

The silacyclopropanes 48 react readily with a wide range of carbonyl compounds, efficiently converting alkanes to oxasilacyclopentanes and providing a useful synthetic tool in organic synthesis (Equation 7) <2004JOC4007>. 

SYNTHESIS OF THREE-MEMBERED RINGS WITH ONE SILICON ATOM 1.09.6.1 Silacyclopropanes... 

Development of reactions of silacyclopropanes as new methods for stereoselective organic synthesis 00ACR813. 

The transition-metal-catalyzed [2 + 2 + 1] cycloaddition of two alkynes and heteroatom sources is a useful method for the synthesis of five-membered heterocycles. For example, a silylene species reacts with two alkynes 64 in the presence of nickel or palladium catalyst to afford substituted siloles 65 and 66. Various silylene equivalents, such as disilanes 67 [24], silacyclopropenes 68 [25], 69 [26], cyclotrisilanes 70 [27], alkylidenesilacyclopropanes 71 [28], silacyclopropanes 72, and 73 [29], have been developed as shown in Scheme 6.21. However, the utility for organic synthesis has been limited, due to the difficulty of those organosilane syntheses and the narrow alkyne scope. 

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