- Cyclic dienol ethers
-
The claimed invention relates to cyclic dienol ethers of formula (III). wherein R3is hydrogen and R4is C1-4alkoxy or R3and R4together form an optionally substituted methylenedioxy group —O—C(R5/
- -
-
Page column 32
(2008/06/13)
-
- Process for making 4,4′-diketo-carotenoids
-
A process for the manufacture of a symmetrical, terminally ring-substituted polyenes by reacting a polyene di(O,O-dialkyl acetal) with a cyclic dienol ether in the presence of a Lewis or Br?nsted acid, hydrolyzing the condensation product resulting therefrom and cleaving off alcohol under basic or acidic conditions from the polyene derivative produced at this stage. The novel cyclic dienol ethers, as well as, novel intermediates resulting from the condensation and additional intermediates in this process form further aspects of the invention. The final products are primarily carotenoids, which find corresponding use, e.g., as colorings and pigments for foodstuffs, animal products, etc.
- -
-
-
- Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6-Oxo-isophoron. II. Ein neues Konzept fuer die Synthese von (3RS,3'RS)-Astaxanthin
-
Starting from 6-oxo-isophorone (2) a new concept for a seven-step synthesis of (3RS,3'RS)-astaxanthin (1) has been developed.As a key feature of the new approach, the oxidation state of astaxanthin (1) is adjusted already at an early stage of the synthesis.Thus, manipulation on more complex intermediates later in the synthesis is reduced to a minimum.Acetonide 10 or dimer 13 represent the key intermediates of this concept (Scheme 2).The whole sequence has been run on a kg scale with an overall yield of 52percent (s.Scheme 5).
- Widmer, Erich,Zell, Reinhard,Broger, Emil Albin,Crameri, Yvo,Wagner, Hans Peter,et al.
-
p. 2436 - 2446
(2007/10/02)
-