Abstract:
Bis-aldolization of aryl alkyl ketones as well as cyclic ketones with paraformaldehyde in the presence of catalytic amount L-proline and low concentration of aqueous sodium hydroxide has been developed in excellent yields. Further, these bis-aldols (1a–8a) are elaborated to corresponding spirocyclic dioxanes (9–16a) and novel spirocyclic trioxocanes (10b–16b) in the presence of p-toluene sulfonic acid. The structure and preferred conformation of these eight membered spirocyclic 1,3,5–trioxocanes is discussed.
