Photochemical reactions. 152nd Communication. Photochemistry of acylsilanes; photolysis and thermolysis of cyclopropyl silyl ketones
作者:Markus E. Scheller、Bruno Frei
DOI:10.1002/hlca.19900730420
日期:1990.6.20
The photolysis and thermolysis of the Cyclopropyl silyl ketones 3, 4, and 5 are described. On n,π* 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
描述了环丙基甲硅烷基酮3、4和5的光解和热解。在n,π*激发下,甲硅烷基酮3和4经历Norrish -II型反应,该反应涉及γ-H的提取,环丙基环的裂解,然后分别逆向烯化为酰基硅烷6和(E / Z)-12。作为3和4的共同产物,二氢呋喃7是通过环丙基部分的C(α)-C(β)交替裂解形成的。化合物6,7,和(E / Z)-12是新型的酰基硅烷光产品。酰基硅烷5的辐射产生了类似的二氢呋喃15作为唯一产物。在3和4的光解中,还发现了衍生自甲硅烷氧基卡宾中间体的产物8A + B和13A + B。在3和4的热分解下,酰基硅烷6(80%)和(E)-12(33%)和(Z)-12(34%)分别是唯一的产品。它们的形成可能通过[1,5]σH位移发生。5的热解产生了二烯16,其形成可以通过将甲硅烷氧基卡宾插入相邻的环丙烷中而导致作为热不稳定中间体的环丁烯28来解释。