Singh Vishwakarma, Pal Shantanu, Mobin Shaikh M
Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, India.
J Org Chem. 2006 Apr 14;71(8):3014-25. doi: 10.1021/jo052544v.
A novel, general, and stereoselective route to functionalized bridged bicyclo[2.2.2]octanes, bicyclo[3.3.0]octanes, bicyclo[4.2.0]octanes, and tricyclo[4.3.1.0(3,7)]decanes has been described. Various functionalized and substituted bicyclo[2.2.2]octanes endowed with a beta,gamma-enone chromophore were synthesized via cycloaddition of in situ generated cyclohexa-2,4-dienones with electron-deficient 2pi partners and manipulation of the resulting adducts. Triplet sensitized irradiation of bridged bicyclooctenones led to synthesis of bicyclo[3.3.0]octanoids, whereas the direct irradiation furnished bicyclo[4.2.0]octanes in stereoselective fashion as a result of modulation of reactivity in excited states. Further, manipulation of the adducts led to appropriately appended and functionalized bicyclo[2.2.2]octanes that upon radical induced cyclization provided an efficient and stereoselective route to the tricyclo[4.3.1.0(3,7)]decane (isotwistane) framework of pupukeananes.
已报道了一种新颖、通用且立体选择性地合成官能化桥联双环[2.2.2]辛烷、双环[3.3.0]辛烷、双环[4.2.0]辛烷和三环[4.3.1.0(3,7)]癸烷的方法。通过原位生成的环己-2,4-二烯酮与缺电子的2π反应物进行环加成反应，并对所得加合物进行处理，合成了各种带有β,γ-烯酮发色团的官能化和取代双环[2.2.2]辛烷。桥联双环辛烯酮的三线态敏化辐照导致双环[3.3.0]辛烷类化合物的合成，而直接辐照由于激发态反应性的调节以立体选择性方式提供双环[4.2.0]辛烷。此外，对加合物的处理得到了适当连接和官能化的双环[2.2.2]辛烷，这些双环[2.2.2]辛烷在自由基诱导环化后提供了一条高效且立体选择性地合成普库卡烷三环[4.3.1.0(3,7)]癸烷（异扭曲烷）骨架的途径。
