Revision and confirmation of the regiochemistry of isoxazoles derived from methyl oleanonate and lanost-8-en-3-one. Synthesis of a new lanostane triterpenoid with a cyano-enone functionality in ring A.
It was previously reported that methyl oleanonate (5) and lanost-8-en-3-one (10) give predominantly [3,2-c]isoxazoles. On the contrary, we have confirmed that both compounds 5 and 10 do not give [3,2-c]isoxazoles but rather afford regioselectively [2,3-d]isoxazoles in good yields. Consequently, a new lanostane triterpenoid with a cyano-enone functionality in ring A was synthesized in two steps from the corresponding [2,3-d]isoxazole, which is interesting from the perspective of biological activity because lanosterol is the biogenetic precursor of steroids.
Honda
Yukiko
Y
Department of Chemistry, Dartmouth College, 6128 Burke Laboratory, Hanover, NH 03755, USA.
Honda
Tadashi
T
Roy
Sujata
S
Gribble
Gordon W
GW
D003500:Cyclization; D007555:Isoxazoles / Q000032:analysis / Q000737:chemistry*; D007810:Lanosterol / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000737:chemistry*; D013237:Stereoisomerism; D014315:Triterpenes / Q000138:chemical synthesis* / Q000737:chemistry*
D007555:Isoxazoles; D014315:Triterpenes; D007810:Lanosterol; D009828:Oleanolic Acid