申请人:Zambon S.p.A.
公开号:US04697036A1
公开(公告)日:1987-09-29
A new enantioselective process is described for preparing optically active alpha-arylalkanoic acids by: (a) halogenation on the aliphatic carbon atom alpha to the ketal group, of ketals of formula ##STR1## in which Ar represents an aryl, optionally substituted; R represents a C.sub.1 -C.sub.4 alkyl; R.sub.1 and R.sub.2, represents a hydroxy, a O.sup.- M.sup.+, OR.sub.3 or NR.sub.4 R.sub.5 group; the carbon atoms indicated by an asterisk both simultaneously are in (R) or (S) configuration. This reaction is diastereoselective, so that a misture of alpha-haloketals is obtained in which one of the two epimers prevails, and generally strongly prevails, over the other. (b) rearrangement of the haloketals of formula ##STR2## in which X is Cl, Br or I to alpha-arylalkanoic acids in a single stage or in two successive stages, by way of esters of formula ##STR3## The compounds (A) and (C) are all new compounds. The rearrangement step (b) may be performed under new, inventive conditions. The esters of formula (C) have pharmacological activity analogous to that of the corresponding alpha-arylalkanoic acids.
本文描述了一种新的对映选择性过程,用于通过以下方法制备光学活性的α-芳基烷基酸:(a)对式为##STR1##的缩醛进行α位于缩醛基团处的脂肪碳原子的卤化,其中Ar表示芳基,可选取取代基;R表示C.sub.1-C.sub.4烷基;R.sub.1和R.sub.2表示羟基、O.sup.- M.sup.+, OR.sub.3或NR.sub.4 R.sub.5基团;由星号标记的碳原子同时处于(R)或(S)构型中。该反应是对映异构选择性的,因此得到α-卤代缩醛的混合物,其中两个外消旋体中的一个占优势,通常强烈占优势。(b)通过式为##STR2##的卤代缩醛的重排,在一个或两个连续的阶段中,通过式为##STR3##的酯的方式制备α-芳基烷基酸。化合物(A)和(C)都是新化合物。重排步骤(b)可以在新的、有创新性的条件下进行。式为(C)的酯具有类似于相应的α-芳基烷基酸的药理活性。