A convenient and asymmetric protocol for the synthesis of natural products containing chiral alkyl chains via Zr-catalyzed asymmetric carboalumination of alkenes. Synthesis of phytol and vitamins E and K.
[reaction: see text]. A convenient and asymmetric protocol for the synthesis of chiral oligoisoprenoids is described. Typically, a C14 vitamin E side chain 5 was synthesized in 47% yield over four steps. Isomeric purity of 5 was upgraded to >99% R at C-2 and 97% R at C-6 by the statistical formation of stereoisomeric p-phenylenebisurethanes and their diastereomeric separation. In addition, phytol and vitamin K were synthesized in 21% and 28% overall yields, respectively, over five steps from 1.
Huo
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Herbert C. Brown Laboratories of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393, USA.
Negishi
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E
D000475:Alkenes / Q000737:chemistry; D000478:Alkylation; D000535:Aluminum / Q000737:chemistry; D001688:Biological Products / Q000138:chemical synthesis; D002384:Catalysis; D009942:Organometallic Compounds / Q000737:chemistry; D010836:Phytol / Q000138:chemical synthesis*; D013237:Stereoisomerism; D014810:Vitamin E / Q000138:chemical synthesis*; D014812:Vitamin K / Q000138:chemical synthesis*; D015040:Zirconium / Q000737:chemistry
D000475:Alkenes; D001688:Biological Products; D009942:Organometallic Compounds; D014812:Vitamin K; D014810:Vitamin E; D010836:Phytol; D015040:Zirconium; D000535:Aluminum