New Trimethylenemethane Dianion Synthons: Application to the Preparation of Substituted Perhydrofuro[2,3-b]furans

The reaction of 3-chloro-2-(chloromethyl)prop-1-ene (1) with lithium powder and a catalytic amount of naphthalene in the presence of different electrophiles in THF at −78°C yields products 2. When carbonylic compounds are used as electrophiles the corresponding methylenic diols are obtained, which by tandem hydroboration–oxidation with alkaline hydrogen peroxide and treatment with PCC (for ketone derivatives) or (Ph3P)3RuCl2 (for aldehyde derivatives) furnish the expected perhydrofurofurans 3. Using 2-chloromethyl-3-(2-methoxyethoxy)prop-1-ene (4) as starting material and under the above conditions, the selective chloro/lithium exchange versus the allylic carbon–oxygen bond cleavage allows the introduction of a first electrophile at −78 to −30°C, and a second electrophile at −30°C to room temperature to give products 5. The same oxidation protocol mentioned above, when applied to diols 5, lead to the differently substituted perhydrofurofurans 7.