1 bearing an amino group protected by an electron-withdrawing group were smoothly cyclized to 2-(silylmethyl)pyrrolidines 2. This cyclization was utilized for the stereoselectivesynthesis of 2,n-disubstituted pyrrolidines (n = 3-5). The cyclized products could be converted to the corresponding alcohols by oxidative cleavage of the carbon-silicon bond with TBAF and H2O2.
[反应:见正文]在酸催化剂的存在下,将带有被吸电子基团保护的氨基的乙烯基硅烷1平滑环化为2-(甲硅烷基甲基)吡咯烷2。该环化反应用于2的立体选择性合成正二取代的吡咯烷(n = 3-5)。通过用TBAF和H 2 O 2氧化碳-硅键,可以将环化产物转化为相应的醇。
Radical Cyclizations Leading to the Bicyclo[2.2.1]heptane Framework: A New Radical Approach to (±)-(<i>Z</i>)-β-Santalol
Tandem radical cyclizations of acyclic iodides, including [3-(2-iodoethyl)-6,10-dimethyl-undeca-5,9-dien-1-ynyl]-dimethylphenylsilane lead in good yields to bicyclo[2.2.1]heptane derivatives. The cascade relies on two sequential radical-mediated 5-exocyclizations. The radical approach is illustrated with the total synthesis ofracemic-(Z)-β-santalol. The results are remarkable, two fused rings and one