Chemistry 634: Advanced Organic Chemistry – Synthesis and Reactivity
Fall 2013, University of Delaware
Prof. Donald Watson
Problem Set 6 Due Beginning of Class 12/03/13
You may work in groups, unless otherwise noted. Do not try to fit answers on these pages, use
separate paper.
1) Provide the missing reagents. Note more than one step may be needed.
OH
Me
R
R
R
Me
R
Me
Me
t-Bu
t-Bu
OTBS
Me
O
Me
O
OH
R
OH
R
R
this enant. only
OH
R
R
R
OH
R
OMe
O
R
O
O
R
R
R
R
OH
R
Ph
R
O
R
Bu
CO2Me
O
R
R
R
Et
R
O
Ph
R
CO2Me
R
Bu
CO2Me
O
R
R
R
Bu
Ph
OTBS
2)
a) In class, we have discussed that Lewis acids can promote the formation of oxo-carbenium ions
and trigger the addition of allyl silanes to them. Sometimes the oxo-carbenium ion can form from a
suitably protected alcohol and an aldehyde. Given that major hint, rationalize the following transformation
including the stereochemical outcome (DO NOT LOOK UP THE ANSWER TO THIS).
O
OTMS
Me
Me
BnO
CO2Me
SiMe2Ph
H
BnO
TMSOTf
-50 °C
O
CO2Me
1, dr = 10:1
b) After 1 was prepared, it was converted to 2 in three steps. What reagents could be used to
carry out this sequence?
3 steps
Me
BnO
O
Me
CO2Me
BnO
1
O
OTBS
2
3) Predict the outcome of the following transformation and illustrate model to predict stereochemistry.
Me
Me
H
Me
Cy2BH, then H2O2
H
H
H
AcO
4) Provide a synthesis of (+)-disparlure starting from materials commercially available from major
chemical companies (ie Aldrich, Acros, Strem, etc). Show all steps. Your synthesis should be expected
to provide highly enantioenriched product. Provide a catalog number for each starting material. You
may use online or paper catalogs for this problem. DO NOT USE SCIFINDER OR BEILSTIEN.
Me
Me
O
Me
(+)-disparlure
5) Provide a synthesis of the following compound from materials commercially available from major
chemical companies (ie Aldrich, Acros, Strem, etc). Show all steps. Your synthesis should be expected
to provide highly enantioenriched or enantiopure product. Provide a catalog number for each starting
material. You may use online or paper catalogs for this problem. DO NOT USE SCIFINDER OR
BEILSTIEN.
Me
Me
O
O
H
OMe