851. The generation, regioselective cyclization and synthetic use of electron-donating heteroatom substituted 2,3-dihydro-2,3-bis(methylene)furans.
- Author
-
Chen, Huai Gu
- Subjects
- Bis, Cyclization, Dihydro, Donating, Electron, Furans, Generation, Heteroatom, Methylene, Regioselective, Substituted, Synthetic, Use
- Abstract
New methods for the generation of amino and oxazolidine substituted 2,3-dihydro-2,3-bis(methylene)furans have been developed. Highly regioselective Diels-Alder type adducts were obtained from the cyclization of these substituted 2,3-dihydro-2,3-bis(methylene)furans with unsymmetrical dienophiles. The regio- and stereochemistry of the cycloaddition reactions are discussed. The synthesis of precursors for the generation of these furan-2,3-quinodimethanes from readily available materials is described. Another new method to generate the carbamate substituted 2,3-dihydro-2,3-bis(methylene)furans and their intramolecular cychzations with dienophiles is described. In order to build up the precursors for the intramolecular cyclizations of the furan-2,3-quinodimethane, a new method is developed to introduce the alkene side chain to the furan ring by direct alkylation of the N-methyl-2,4-dimethyl-3-furaldimine with haloalkenes. The regio- and stereochemistry of the intramolecular cyclizations are also discussed. As an application of the heteroatom substituted 2,3-dihydro-2,3-bis(methylene)furans, an approach of the total synthesis of a natural product farfugin A is described. The potential of the further conversion of the substituted groups on the cycloadducts and improvement of the synthetic efforts in the intramolecular cyclization of furan-2,3-quinodimethanes with triple bonds are also discussed.
- Published
- 1988