摘要:
Stereo selective inverse-demand [4+2] cycloadditions of 3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine and dimethyl 1,2,4,5-tetrazine3,6-dicarboxylate to 4'-methylenedihydro-3'H-spiro[bicyclo[2.2.1]heptane-2,2'-furans] and 4'-methylene-1'-(4-nitrophenyl)spiro[bicyclo(2.2.1]heptane-3,2'-pyrrolidine] were studied. Cycloadditions took place stereoselectively at the exocyclic C=C double bonds to give novel 11: 14-isopropylidene-14-methyl-2,3-diaza-8-oxadi spi to [5.1.5.2]pentadecane and 11: 14-isopropylidene-11-methyl-2,3,8-triazadispiro[5.1.5.2]pentadecane derivatives in 50-98% de. The structures of the novel dispiro compounds were determined by NMR techniques, NOESY spectroscopy and X-ray diffraction. (c) 2007 Elsevier Ltd. All rights reserved.