PROBLEMS
December11,2008
1.ͲMitchellandcoworkersatLillyreportedageneralstudy,basedonworkbyMcLoughlin,ofthe
reduction of various carbonates of 2Ͳhydroxyacetophenone derivatives (1) with NaBH4.
Interestingly, the reactions afford the deoxygenated compounds (2) in good yield. Provide a
plausiblemechanismforthisreaction.
O
MeO
O
OH
O
R
R
NaBH4
75-93%
X
1
X
2
2.Ͳ A synthesis of lycoramine was published in 2004. A sequence from the report is provided
below. Provide a mechanism for the overall transformation (A to B) that explains the high
diastereoselectivityofthisprocess.YouranswershouldhighlightintermediateX.
N
NHTs
1)nBuLi, TMEDA
2)
OTBS
A
H
O
CHO
NBS (1.1equiv)
X
*
i-PrOH
93%
>99:1 d.r.
OMe
OTBS
*
*
TBSO
Br
B
OMe
OTBS