Domino Strategy for the Stereoselective Construction of Angularly Fused Tricyclic Ethers

A stereoselective
synthesis of decahydrofuro­[3,2-d]­isochromene
derivatives has been achieved by the
condensation of 2-cyclohexenylbutane-1,4-diol with aldehydes in the
presence of a stochiometric amount of BF3·OEt2 in dichloromethane at −78 °C. Similarly, the
condensation of 2-cyclopentenylbutan-1,4-diol with aldehydes provides
the corresponding octahydro-2H-cyclopenta­[c]­furo­[2,3-d]­pyran derivatives
in good yields with high diastereoselectivity. It is an elegant strategy
for the quick construction of tricyclic architectures with four contiguous
stereogenic centers in a single step. These tricyclic frameworks are
the integral part of numerous natural products.