Disilanes transition-metal substituted

L. Transition Metal-substituted Disilanes and Related Compounds. 1260... 

Metallodisilanes LnM-SiX2-SiX3 (X = H, Cl) represent interesting model compounds for the study of the transition metal effect , because these species contain both a transition metal substituted- as well as a metal-ffee Si-X unit in the same molecule. EtsN-assisted hydrolysis of the ferrio-pentachlorodisilane Cp(OC)2Fe-Si2Cl5 yields exclusively the ferriodichloro-trihydroxy-disilane 10, demonstrating the reduced susceptibility to nucleophilic attack at the silicon in the a-position to the transition metal atom. ... 

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. 

The Si-B bond in silylboranes are activated in the manner similar to disilanes by the group 10 transition metal catalysts to mediate silylboration of such unsaturated substrates including alkenes, alkynes, 1,2-, and 1,3-dienes. Catalytic enantioselective silylboration of 1,2-dienes has been achieved with a chiral palladium catalyst to give a-boryl-substituted chiral allylsilanes. The resulting C-B bonds are converted into various types of C-C, C-N, and C-O bonds by the rich chemistry of organoboron reagents (Scheme 3 1). ... 

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