Substituent control in the synthesis of tetrahydropyrans, oxepanes and oxocanes by episulphonium ion-mediated cyclisation
作者:Pedro L. López-Tudanca、Keith Jones、Peter Brownbridge
DOI:10.1016/s0040-4039(00)79697-3
日期:1991.5
Cyclisation of the heptenols (1) to cyclic ethers via episulphonium ions has been studied and the effect of allylic substituents on the size of ring produced has been explored.
Initiating radical cyclizations by H transfer from transition metals
作者:John Hartung、Mary E. Pulling、Deborah M. Smith、David X. Yang、Jack R. Norton
DOI:10.1016/j.tet.2008.10.030
日期:2008.12
diphosphine) can be used to initiate radicalcyclizations by transferring H to activated terminal olefins. CpCr(CO)3H can catalyze reductive cyclizations, with H2 as the ultimate reductant. Appropriate substrates can be assembled by the Morita–Baylis–Hillman reaction of methyl acrylate with an aldehyde. Six- as well as five-membered rings can be formed, and a tandem cyclization to decalin can be effected.