The synthesis of trisubstituted tetrahydrofurans via the use of an organoselenium-mediated cyclisation reaction

The dianion derived from methyl acetoacetate may be alkylated selectively on the γ-carbon atom to form a 1,2-addition product (1) with acrolein. This material after protection as its dimethyl-t-butylsilyl derivative (2) can be cyclised with N-phenylselenophthalimide (NPSP) in the presence of various catalysts to afford dihydrofuran derivatives which are useful precursors for hydroxy-containing trisubstituted tetrahydrofurans. The X-ray crystal structure of methyl cis-4-dimethyl-t-butylsilyloxy-5- phenylselenomethyltetrahydrofuran-2-ylideneacetate, compound (4), have also been determined.