Vk. Aggarwal et al., THE FIRST SYNTHESIS OF THE NOVEL 2,8-DIOXABICYCLO[3.2.1]OCTANE RING-SYSTEM - A KEY FEATURE OF THE SQUALESTATINS, Journal of the Chemical Society, Chemical Communications, (1), 1994, pp. 87-88
The lithium enolate of the acetonide of (S,S)-dimethyl tartrate 5 was
prepared by treatment with lithium diisopropylamide in the presence of
12-crown-4, and added to acetonylacetone 6; reaction of the product w
ith acid gave a mixture of cyclised adducts from which a single diaste
reoisomer was isolated and shown to have a structure consistent with t
he core of squalestatin.