PROBLEMS
JUNE 16, 2009.
1.‐
In
1979,
Deslongchamps
and
his
team
of
students
at
University
of
Sherbrooke
in
Canada
disclosed
a
beautiful
synthesis
of
the
poly‐oxygenated
diterpene,
(+)‐
ryanodol.
An
important
transformation
that
established
a
mono‐protected
ceto‐
quinone
intermediate
is
illustrated.
Please
provide
a
mechanism
for
this
transformation.
O
O
1eq NaOH
H2O, CH3CN;
O
O
O
O
NBS
O
2.‐
The
following
transformation
is
a
key
step
n
Boeckman’s
synthesis
of
laurenyne.
Provide
a
mechanism.
TBSO
PMBO
OH
OH
Dess-Martin
Periodinane
22° to 45°C
92%
TBSO
CHO
O
OPMB