Selective Syntheses of Planar-Chiral Ferrocenes

Publisher Summary This chapter discusses the recent results on the photochemical generation and reactions of the silylenes and silicon–carbon double-bonded intermediates. The photochemical behavior of monosilanes has been investigated by mercury-sensitized photolysis, flash photolysis, vacuum ultraviolet photolysis, and matrix photolysis. All of the cyclic and acyclic permethylpolysilanes with the exception of hexamethyldisilane readily undergo photolysis on irradiation with ultraviolet light to give shorter chain compounds with the concurrent generation of the divalent silicon intermediate, dimethylsilylene. The silylene species generated during photolysis are thought to polymerize in the absence of a trapping agent. The photolysis of branched permethylpolysilanes is of considerable interest, because a novel silylene intermediate––trimethylsilylmethylsilylene––is produced. The photolysis of phenyl-substituted polysilanes also affords a convenient method for the generation of silylene species. The stereochemistry of photochemical generation of dimethylsilylene is reported. Hydrosilanes are one of the most suitable silylene trapping agents and are often used in photolysis. The yields of the silacyclopropanes are highly dependent on the structure of the olefins used. When tetramethylethylene is used as a quencher, only a trace of the methoxysilane is obtained along with small amounts of the silylalkenes.

Photochemistry of Organopolysilanes

Hetero-π-systems from 2+2 cycloreversions. Part 1. Gusel'nikov–Flowers route to silenes and origination of the chemistry of doubly bonded silicon

Stereochemistry of Metallocenes

Four-membered rings can be cleaved thermally, Photochemically, or catalytically into two π bonded fragments. Theoretical calculations, kinetic studies, and investigations of stereo- and regioselectivity have been undertaken to clarify the question of whether the reaction involves one or two steps and to permit predictions on its course. [2 + 2]-Cycloreversions have been used to clarify the structure of four-membered rings, to prepare highly reactive π electron-systems and–in combination with a [2 + 2]-cycloaddition–to protect double bonds. The combination of a cycloaddition and-reversion can be used to convert a carbonyl group into an olefin. Starting with compounds containing annelated four-membered rings, compounds with two functional groups or large ring systems can be prepared. [2 + 2]-Cycloreversions have also been discussed in connection with storage of solar energy.

[2 + 2]‐Cycloreversions

Pyrolytic and photochemical fragmentation of 1,1-dimethyl-2-phenyl-1-silacyclobutane

Copyrolysis of 1,1-dimethyl-1-silacyclobutane and acrolein

Pyrolysis of 1-phenyl-1,3-butadienes. New synthesis of 1,2-dihydronaphthalenes

Synthesis and pyrolysis of 1,1-dimethyl-2-phenyl-1-silacyclobut-2-ene

Asymmetric induction, time and solvent dependence in the metallation of perrocenylalkyl ethers

Phillip B. Valkovich

Papers

Pyrolytic and photochemical fragmentation of 1,1-dimethyl-2-phenyl-1-silacyclobutane

Copyrolysis of 1,1-dimethyl-1-silacyclobutane and acrolein

Pyrolysis of 1-phenyl-1,3-butadienes. New synthesis of 1,2-dihydronaphthalenes

Synthesis and pyrolysis of 1,1-dimethyl-2-phenyl-1-silacyclobut-2-ene

Asymmetric induction, time and solvent dependence in the metallation of perrocenylalkyl ethers