80738-05-2Relevant academic research and scientific papers
96. Photochemical Reactions Photochemistry of Acylsilanes: Photolysis and Thermolysis of Cyclopropyl Silyl Ketones
Scheller, Markus E.,Frei, Bruno
, p. 922 - 931 (2007/10/02)
The photolysis and thermolysis of the cyclopropyl silyl ketones 3, 4, and 5 are described.On n,?* excitation, the silyl ketones 3 and 4 undergo a Norrish-type-II reaction involving γ-H abstraction, cyclopropyl ring cleavage followed by retro-enolization to the acylsilanes 6 and (E/Z)-12, respectively.As a common product of 3 and 4, the dihydrofuran 7 is formed via the alternative C(α)-C(β) cleavage of the cyclopropyl moiety.Compounds 6,7, and (E/Z)-12 are new types of acylsilane photoproducts.The irradiation of acylsilane 5 gave the analogous dihydrofuran 15 as the only product.On photolysis of 3 and 4, products 8A + B and 13A + B, derived from a siloxy carbene intermediate, were found as well.On thermolysis of 3 and 4, the acylsilanes 6(80percent), and (E)-12(33percent) and (Z)-12(34percent), respectively, are formed as the only products.Their formation may occur via a sigmatropic H-shift.The thermolysis of 5 gave the diene 16 whose formation can be explained by insertion of a siloxycarbene into the neighboring cyclopropane leading to the cyclobutene 28 as thermally unstable intermediate.
