申请人:Radspieler Alexander
公开号:US20050014976A1
公开(公告)日:2005-01-20
A process for the manufacture of retinal (I) comprises reacting a 5-(2,6,6-trimethyl-cyclohex-1-enyl)-1,4-pentadiene derivative (IIa) or a 5-(2,6,6-trimethyl-cyclohex-2-enyl)-1,4-pentadiene derivative (IIb) or a 5-(2,6,6-trimethyl-2-cyclohexen-1-ylidene)-1-pentene derivative (IIc) or a 5-(2,6,6-trimethyl-cyclohex-1-enyl)-penta-1-en-4-yne derivative (IId) or a 5-(2,6,6-trimethyl-cyclohex-2-enyl)-penta-1-en-4-yne derivative (IIe) with a 1,3-butadiene derivative H2C═C(CH3)CCH═CHOR4 (III) in the presence of a Lewis or Brönsted acid and subjecting the compound obtained in each case [(IVa), (IVb), (IVc), (IVd) or (IVe), respectively] to basic or acidic conditions to eliminate therefrom the moiety R2H and thus produce, according to the immediate precursor, retinal itself or a particular derivative thereof [(I′), (I′), (Va) or (Vb), respectively] and, where in two cases such derivative is produced featuring a triple bond [derivative (Va) or (Vb)], hydrogenating this to produce retinal (I) or the derivative (I′), respectively, and each case where a derivative (I′) or (I′) has been produced, isomerizing this under basic or acidic conditions or in the presence of a metal catalyst to the desired retinal (I). The so-produced retinal is usually in the form of an isomeric mixture, normally as (9 E/Z, 13 E/Z)-retinal, and this can be isomerized according to a further inventive aspect to (all-E)-retinal by the acid-catalysed formation of an adduct of (all-E)-retinal with hydroquinone in crystalline form. The so obtained (all-E)-retinal-hydroquinone adduct can then if desired be converted to vitamin A alcohol in the predominantly (all-E)-isomeric form by a method known per se. The novel starting materials (IIa), (IIb), (IIc), (IVI) and (IIe) represent a still further inventive aspect. Retinal is a valuable intermediate in the synthesis of further vitamin A compounds (retinoids). The retinoids, particularly vitamin A alcohol (retinol), are known to be valuable substances which promote the well-being of humans, inter alia in respect of vision, the immune system and growth, and for this reason are often used as components of multivitamin preparations and as additives for certain food- and feedstuffs.
制备
视黄醛(I)的过程包括在路易斯或布朗斯特酸的存在下,将5-(2,6,6-三甲基
环己-1-烯基)-
1,4-戊二烯衍
生物(IIa)或5-(2,6,6-三甲基环己-2-烯基)-
1,4-戊二烯衍
生物(IIb)或5-(2,6,6-三甲基-2-
环己烯-1-基)-1-
戊烯衍
生物(IIc)或5-(2,6,6-三甲基
环己-1-烯基)-戊-1-烯-4-炔衍
生物(IId)或5-(2,6,6-三甲基环己-2-烯基)-戊-1-烯-4-炔衍
生物(IIe)与
1,3-丁二烯衍
生物H2C═C(
CH3)CCH═CHOR4(III)反应,并在每种情况下得到的化合物[(IVa),(IVb),(IVc),(IVd)或(IVe),分别]在酸性或碱性条件下消除其R2H基团,从而根据直接前体制备
视黄醛本身或特定衍
生物[(I′),(I′),(Va)或(Vb),分别],在两种情况下产生带有三键的衍
生物[(Va)或(Vb)],将其加氢以产生
视黄醛(I)或其衍
生物(I′),并在每种情况下,产生衍
生物(I′)或(I′)后,在碱性或酸性条件下或在
金属催化剂的存在下使其异构化为所需的
视黄醛(I)。所生产的
视黄醛通常是以异构混合物的形式存在,通常为(9 E/Z,13 E/Z)-
视黄醛,可以根据进一步的发明方面将其异构化为(全E)-
视黄醛,方法是在晶体形式下通过酸催化形成(全E)-
视黄醛与
对苯二酚的加合物。然后,如有需要,可以将所获得的(全E)-
视黄醛-
对苯二酚加合物转化为主要为(全E)-异构体的
维生素A醇,这是一种已知的方法。新的起始材料(IIa),(IIb),(IIc),(IVI)和(IIe)代表了另一个创新方面。
视黄醛是合成进一步
维生素A化合物(视黄
醇类)的有价值中间体。视黄
醇类,特别是
维生素A醇,已知是有价值的物质,可以促进人类的健康,包括视力,免疫系统和生长等方面,并因此经常用作多种
维生素制剂的组分和某些食品和饲料的添加剂。