110436-57-2Relevant academic research and scientific papers
Alkenes as alkyne equivalents in radical cascades terminated by fragmentations: Overcoming stereoelectronic restrictions on ring expansions for the preparation of expanded polyaromatics
Mohamed, Rana K.,Mondal, Sayantan,Gold, Brian,Evoniuk, Christopher J.,Banerjee, Tanmay,Hanson, Kenneth,Alabugin, Igor V.
, p. 6335 - 6349 (2015)
Chemoselective interaction of aromatic enynes with Bu3Sn radicals can be harnessed for selective cascade transformations, yielding either Sn-substituted naphthalenes or Sn-indenes. Depending on the substitution at the alkene terminus, the initial regioselective 5-exo-trig cyclizations can be intercepted at the 5-exo stage via either hydrogen atom abstraction or C-S bond scission or allowed to proceed further to the formal 6-endo products via homoallylic ring expansion. Aromatization of the latter occurs via β-C-C bond scission, which is facilitated by 2c,3e through-bond interactions, a new stereoelectronic effect in radical chemistry. The combination of formal 6-endo-trig cyclization with stereoelectronically optimized fragmentation allows the use of alkenes as synthetic equivalents of alkynes and opens a convenient route to α-Sn-substituted naphthalenes, a unique launching platform for the preparation of extended polyaromatics.
Drawing from a pool of radicals for the design of selective enyne cyclizations
Mondal, Sayantan,Mohamed, Rana K.,Manoharan, Mariappan,Phan, Hoa,Alabugin, Igor V.
supporting information, p. 5650 - 5653 (2013/12/04)
Despite the possibility of intermolecular attack at four different locations, the Bu3Sn-mediated radical cyclization of aromatic enynes is surprisingly selective. The observed reaction path originates from the least stable of the equilibrating pool of isomeric radicals produced by intermolecular Bu3Sn attack at the π-bonds of substrates. The radical pool components are kinetically self-sorted via 5-exo-trig closure, the fastest of the four possible cyclizations. The resulting Sn-substituted indenes are capable of further transformations in reactions with electrophiles.
