| 摘要 |
<p>Reaction is between any conjugated diolefin (I) an formaldehyde, to form a major proportion of dihydropyrane, in presence of a Lewis Acid catalyst e.g. AlCl3,BF3 at 20-150 degrees C, in an essentially non-aqueous solvent pref. an ether e.g. (C2H5)2O, or an aromatic or aliphatic nitrile e.g. benzonitrile, propionitrile. Pref. (I) is 1,3-butadine and the product is comprises a major proportion of 5,6-dihydro - 2H - pyrane.</p> |
