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 electro philes in THF at -78 degrees 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 an d treatment with PCC (for ketone derivatives) or (Ph3P)(3)RuCl2 (for aldehy de derivatives) furnish the expected perhydrofurofurans 3. Using 2-chlorome thyl-3-(2-methoxyethoxy)prop-1-ene (4) as starting material and under the a bove conditions, the selective chloro/lithium exchange versus the allylic c arbon-oxygen bond cleavage allows the introduction of a first electrophile at -78 to -30 degrees C, and a second electrophile at -30 degrees C to room temperature to give products 5. The same oxidation protocol mentioned abov e, when applied to diols 5, lead to the differently substituted perhydrofur ofurans 7. (C) 2000 Elsevier Science Ltd. all rights reserved.