The preparation and binding properties of spirocyclic tetrahydrofurans 7-1 1 are described. The condensation of cyclopentanone with 5-lithio-2, 3-dihydrofuran (12) provided an alcohol which readily rearranged to ketone 14 under acidic conditions." Capping" of the carbonyl group in 14 so as to generate a second spiro tetrahydrofuran subunit gave rise to 7 and 8. Starting with cyclobutanone, 2-fold ring expansion involving 12 provided the key reactions ...