P, y-Carotene

Human plasma Lycopene isomers, a/p/y-carotene Extraction with hexane, centrifugation, saponification with KOH C-18/C-30 ACN-MTBE HPLC/MS/MS/ APCI(+/-) 11.2 fmol for lycopene 32... 

Numerous other syntheses of carotenoids making use of the Wittig reaction have yielded p,y-carotene, optically active y,y-carotene 281), (+)-a-carotene 282), and some... 

Andrewes, A.G.. and Liaaen-Jensen, S., Animal carotenoids. Part 8. Synthesis of P.y-carotene and y.y-carotene, Acta Chem. Scand.. Tl, 1401, 1973. 

Representative carotenoids with the yend group are P,y-carotene (5) and yy-carotene (15). The synthesis of the stereoisomers of these carotenes by the Ci5 + Cio + Ci5 = C4o scheme has been reported [51]. For the synthesis of the Ci5-phosphonium salt 170, racemic y-ionone (171) was used as starting material and was condensed in a Homer-Emmons reaction with ethyl diethyl phosphonoacetate (83) n the presence of sodium methoxide to give 172 in 90% yield. Reduction with UAIH4, followed by reaction with triphenylphosphine hydrobromide, gave the desired phosphonium salt 170 in 70% yield (Scheme 39). 

P,y-Carotene (459) exhibits very similar absorption properties and an electronic spectrum identical with that of a-carotene (458). It is probable, therefore, that the two pigments have been confused in the older literature 674). The pigment P444, detected in several fungi by Arpin 35, 241), is identical with p,y-carotene (459) 41). 

Animal Carotenoids 8. Synthesis of p,y-Carotene and y,Y-Carotene. Acta Chem. 

Hallenstvet, M., R. Buchecker, G. Borch, and S. Liaaen-Jensen Absolute Configuration of P,y-Carotene and Biosynthetic Implications. Phytochem. 16, 583 (1977). 

Optically active (6 i )-P,7-carotene [ent- 69)], prepared from racemic Y-ionone partly resolved via its menthydrazone, had Cotton effect opposite to that of natural p,y-carotene (69), which therefore has the 6 5-configuration (84). 

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