| 摘要 |
<p>A compound of general formula (I), in which each of R?1, R2, R3 and R4¿ independently represent a hydrogen atom or a group -(CO)¿nR?5 in which n is 0 or 1 and R5 represents an alkyl, aryl, cycloalkyl, alkaryl or aralkyl group, or R1 or R2 together and/or R?3 and R4¿ together represent an alkylene group; Q represents an oxygen or sulphur atom; and Y represents a hydrogen atom, an alkali metal atom or a group of the general formula -COA in which A represents a halogen atom or an alkyl, alkenyl or alkoxy group optionally substituted by a phenyl, cycloalkyl, alkoxy or alkylcarbonyl group. Such compounds are cyclic and optically active and are useful in asymmetric syntheses and in the separation of optically active isomers.</p> |
