Highlights from the Synthesis of Gibberellins:

H
Me
Me
O
O
10 steps
37%
Me
H
H
O
Me
H
MeO2C Me
H
H
O
1) Bu 3SnH,
AIBN
2) SiO 2
H
H
Me
Me
O
H
H
HO2C Me
Me H
H
CO 2H
H
Me H
OAc
2) TBAF
Me
OAc
OTES
3:1 at C7
OTES
72% (4 steps)
2) Ac2O Cross, Hanson, JCS, 1963, 2944.
39-GA12-Ihara-formal.cdx 2/5/04 3:04 PM
GA 12 Formal Synthesis: Ihara
1) 200˚C
O
GA 12
SnR 3
Me
1) s-BuLi
O
H
Me
Me H
Me
O
O
A : B
93% (1:18 mix)
O
H
AcO
H
OTES
Me
O
H
5 steps
88%
Ihara, JACS, 2001, 1856.