A biosynthetically-inspired synthesis of the tetrahydrofuran core of obtusallenes II and IV.
[reaction: see text] Sharpless asymmetric dihydroxylation was regioselective for the trans olefin in an E vs Z vs terminal triene substrate. To test a biosynthetic hypothesis, the resulting diol underwent diastereoselective bromoetherification to provide the des-chloro core of marine natural products obtusallenes II and IV. Alternatively, anionic chloride ring-opening of a Z-beta,gamma-unsaturated epoxide gave separable regioisomeric halohydrins. Bromoetherification gave the fully elaborated core of obtusallenes II and IV with all of the relative stereochemistry correctly set.
Braddock
D Christopher
DC
Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, U.K. c.braddock@imperial.ac.uk
Bhuva
Roshni
R
Millan
David S
DS
Pérez-Fuertes
Yolanda
Y
Roberts
Craig A
CA
Sheppard
Richard N
RN
Solanki
Savade
S
Stokes
Elaine S E
ES
White
Andrew J P
AJ
D001688:Biological Products / Q000737:chemistry*; D001966:Bromine / Q000737:chemistry; D004852:Epoxy Compounds / Q000737:chemistry; D004987:Ethers / Q000737:chemistry; D005663:Furans / Q000138:chemical synthesis*; D006900:Hydroxylation; D044722:Laurencia / Q000737:chemistry*; D008386:Marine Biology; D008956:Models, Chemical; D013237:Stereoisomerism
D001688:Biological Products; D004852:Epoxy Compounds; D004987:Ethers; D005663:Furans; C018674:tetrahydrofuran; D001966:Bromine