A novel, selective, and efficient route to carotenoids and related natural products via Zr-catalyzed carboalumination and Pd- and Zn-catalyzed cross coupling.
[structure: see text]. A highly efficient and stereoselective protocol for the syntheses of symmetrical and unsymmetrical carotenoids involving Zr-catalyzed carboalumination of conjugated oligoenynes and Pd- and Zn-catalyzed alkenyl-alkenyl coupling has been developed and applied to the syntheses of beta- and gamma-carotene and vitamin A. gamma-Carotene of > or =99% isomeric purity was prepared in three linear steps (five steps overall) from beta-ionone, enyne 8, (E)-ICH=CHBr, and (E)-Me3SiC triple bond CCH=CHBr in 32% overall yield.
Zeng
F
F
Herbert C. Brown Laboratories of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
Negishi
E
E
D000535:Aluminum / Q000737:chemistry*; D002338:Carotenoids / Q000138:chemical synthesis*; D002384:Catalysis; D009682:Magnetic Resonance Spectroscopy; D010165:Palladium / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
D002338:Carotenoids; D010165:Palladium; D015040:Zirconium; D000535:Aluminum; D015032:Zinc