Highlights from the Synthesis of Gibberellins:

SnR 3
PhO
S
RO
O
R 3Sn-S
O
O
O
O
O
CO
Me
CO
Me
OPh
Me
H
H
H
H
CO 2Me
H
CO 2Me
Bu 3SnH
H
CO 2Me
23-GA-radicalcascade.cdx 2/5/04 11:15 AM
Radical Cascade: Attempted Deoxygenation at C3
OAc
OAc
OAc
Bu 3SnH
R 3Sn-S
O
O
O
O
O
O
equatorial (α)
C3 hydroxyl removed
without event
5-exo
O
O
H
H
Me
Me
H
H
CO 2Me
H
H
CO 2Me
OAc
R 3Sn-S
O
O
OAc
O
O
H
Me
H
5-exo
H
CO 2Me
OAc
Barton, McCombie, JCS Perkin I, 1975, 1574.
Mander,TL, 1996, 4255.
*synthetic application: Sherburn,JACS, 2003, 12108.