Total synthesis of furanether b. construction of a hydroazulene skeleton via a novel [5 + 2] cycloaddition reaction of silyloxyallene

Article abstract of DOI:10.1246/cl.2010.630

A new synthetic method for cycloheptanone derivatives was developed on the basis of a novel [5 + 2] cycloaddition reaction using a dicobalt hexacarbonyl propargyl cation species and a silyloxyallene. The method can be applied for constructing functionalized hydroazulene skeletons, and a total synthesis of sesquiterpene furanether B was achieved through the reactions involving transformation of the dicobalt acetylene complex into a maleic anhydride derivative and the crucial oxidative transannular ether ring formation.