24480-38-4Relevant academic research and scientific papers
Synthesis of (3 R,3 R)-zeaxanthin and its meso -stereoisomer from (3 R,3 R,6 R)-lutein via (3 R)-3,4-anhydrolutein
Khachik, Frederick
experimental part, p. 453 - 459 (2012/03/27)
A process has been developed for the partial synthesis of (3R,3R)-zeaxanthin and (3R,3S; meso)-zeaxanthin from commercially available (3R,3R,6R)-lutein. This involves the regioselective hydroboration of a dehydration product of lutein, namely (3R)-3,4-didehydro-,-caroten-3-ol [(3R)-3,4-anhydrolutein], to yield a mixture of (3R,3R)-zeaxanthin and (3R,3S; meso)-zeaxanthin followed by separation of these carotenoids by enzyme-mediated acylation. (3R,3R,6R)-Lutein, (3R,3R)-zeaxanthin and its meso-isomer accumulate in human ocular tissues and have been implicated in the prevention of age-related macular degeneration (AMD). Georg Thieme Verlag Stuttgart New York.
Process For The Preparation of Beta and Alpha Cryptoxanthin
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Page/Page column title page; 3; 7; 11-12, (2010/12/29)
The present invention relates to a process for converting lutein and/or lutein esters to (3R)-β-cryptoxanthin and (3R,6′R)-α-cryptoxanthin, suitable for human consumption as dietary supplements, by employing safe and environmentally friendly reagents. (3R)-β-Cryptoxanthin and (3R,6′R)-α-cryptoxanthin are two rare food carotenoids that are not commercially available and the former exhibits vitamin A activity. In the first synthetic step, commercially available lutein and/or lutein esters are transformed into a mixture of dehydration products of lutein (anhydroluteins) in the presence of a catalytic amount of an acid. The resulting anhydroluteins are then converted to (3R)-β-cryptoxanthin (major product) and (3R,6′R)-α-cryptoxanthin (minor product) by heterogeneous catalytic hydrogenation employing transition elements of group VIII (Pt, Pd, Rh supported on alumina or carbon) in a variety of organic solvents under atmospheric pressure of hydrogen and at temperatures ranging from ?15° C. to 40° C. Among these catalysts, Pt supported on alumina at 40° C. in ethyl acetate provides the best yield of (3R)-β-cryptoxanthin and (3R,6′R)-α-cryptoxanthin. Several homogeneous catalysts can also promote the regioselective hydrogenation of anhydroluteins to a mixture of (3R)-β-cryptoxanthin and (3R,6′R)-α-cryptoxanthin in low to moderate yields. The catalysts may be transition metal complexes such as palladium acetylacetonate, Rh(Ph3P)3Cl (Wilkinson's catalyst), [(C6H11)3P[C8H12][C5H5N] Ir+PF6? (Crabtree catalyst), or [C8H12][(MePh2P)2]Ir+PF6?. Among these, Wilkinson catalyst converts anhydroluteins to (3R)-β-cryptoxanthin and (3R,6′R)-α-cryptoxanthin in nearly quantitative yield. A novel feature of this invention is the regioselective hydrogenation of anhydroluteins while the highly conjugated polyene chain of these carotenoids remains intact.
Process for Synthesis of (3R,3'R)-Zeaxanthin and (3R,3'S;meso)-Zeaxanthin from (3R,3'R,6'R)-Lutein via (3R)-3',4'-Anhydrolutein
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Page/Page column 7; 9, (2009/10/01)
(3R, 3′R, 6′R)-Lutein and (3R, 3′R)-zeaxanthin are two dietary carotenoids that are present in most fruits and vegetables commonly consumed in the US and accumulate in the human plasma, major organs, and ocular tissues. Another stereoisomer of (3R, 3′R)-zeaxanthin that is not of dietary origin but is found in the human ocular tissues is (3R, 3′S; meso)-zeaxanthin. There is growing evidence that these carotenoids play an important role in the prevention of age-related macular degeneration (AMD) that is the leading cause of blindness in the U.S. and the Western World. In view of the potential therapeutic application of dietary lutein, (3R, 3′R)-zeaxanthin, and (3R, 3′S; meso)-zeaxanthin, the industrial production of these carotenoids is of considerable importance. The present invention provides a process for the partial synthesis of (3R, 3′R)-zeaxanthin and (3R, 3′S; meso)-zeaxanthin from a readily accessible dehydration product of (3R, 3′R, 6′R)-lutein, namely, (3R)-3′,4′-didehydro-β,β-caroten-3-ol [(3R)-3′,4′-anhydrolutein]. The process involves regioselective hydroboration of (3R)-3′,4′-anhydrolutein to a mixture of (3R, 3′R)-zeaxanthin and (3R, 3′S; meso)-zeaxanthin followed by separation of these carotenoids by enzyme-mediated acylation.
PROCESS FOR THE PREPARATION OF ALPHA- AND BETA-CRYPTOXANTHIN
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Page/Page column 14-20; 26-28, (2008/06/13)
The present invention relates to a process for converting lutein and/or lutein esters to β-cryptoxanthin and α-cryptoxanthin, suitable for human consumption as dietary supplements, by employing safe and environmentally friendly reagents. In the first synthetic step, commercially available lutein and/or lutein esters are transformed into a mixture of dehydration products of lutein (anhydroluteins) in the presence of a catalytic amount of an acid. The resulting anhydroluteins are then converted to β-cryptoxanthin (major product) and α-cryptoxanthin (minor product) by heterogeneous catalytic hydrogenation employing transition elements of group VIII in a variety of organic solvents under atmospheric pressure of hydrogen. A novel feature of this invention is the regioselective hydrogenation of anhydroluteins while the highly conjugated polyene chain of these carotenoids remains intact.
Method for production of rare carotenoids from commercially available lutein
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Page/Page column 11-12, (2008/06/13)
Disclosed are processes for conversion of (3R,3′R,6′R)-lutein to (3R,6′R)-α-cryptoxanthin, (3R)-β-cryptoxanthin, anhydroluteins I, II, and III (dehydration products of lutein), and a method for separating and purifying the individual carotenoids including the unreacted (3R,3′R)-zeaxanthin. The invention also includes two methods that transform (3R,3′R,6′R)-lutein into (3R,6′R)-α-cryptoxanthin in excellent yields.
