| 摘要 |
The prepn. of optically active 2-oxetanone derivs. of formula (I) comprises cycloaddition of ketones of formula R3R4C=C=O (III) (which have been obtd. insitu by dehydrochlorination of carboxylic acid chlorides of formula R3R4CH-COCl (II)) and carbonyl cpds. of formula R1R2C=O (IV) in the presence of optically active tert. amines used in an amt. which is less than the stoichiometrically necessary amt., the rest being made up with an optically inactive tert. amine. R1= CXR5R6, X= F, Cl or Br. R5 and R6= each H, F, Cl, Br or opt. halosubstd. alkyl; R2= H, 1-6C alkyl or a gp. R1; R3 and R4= each H, F, Cl, Br, opt. susbtd. alkyl or opt. substd. aryl; or R3= MeO or phthalimido and R4= H; provided that R1=R2 and R3=R4 do not occur simultaneously. USE/ADVANTAGE - (I) are valuable chiral building blocks which can be converted into a wide variety of optically pure prods. The use of the optically inactive tert-amine in the presence of a catalytic amt. of optically active tert. amine (known as a catalyst for the enantiomer selective cycloaddition and for the conversion of (II) into (III)) enables (I) to be prepd. in good yields and optical purity. Using optically active tert. amine alone would be too expensive for use on a commercial scale.
|
