Chemistry 634: Advanced Organic Chemistry – Synthesis and Reactivity
Fall 2013, University of Delaware
Prof. Donald Watson
Problem Set 3 Due Beginning of Class 10/10/13
You may work in groups, unless otherwise noted. No not try to fit answers on these
pages, use separate paper.
1) Predict the product for each of the following transformations and provide a
mechanism.
1) BuLi, THF, –50 °C,
then (CH2O)n, –50 °C to rt
2) I2, PPh3, imid
O
O
O
C12H17O3I
Me
O
1) tBuLi (2 equiv),
then CO2
2) HCl
3) MeI,K2CO2
O
C8H10O3
I
Me3Si
F
NO2
N
Na
SiMe3
C17H16N2O2
Me
N
THF, 60 °C
F
CF3
O
CN
NH2
NaH, then HCl
C12H9F3N2O
Me
2) Please provide a mechanism for the following reaction and explain the observed
selectivity.
NMe2
NMe2
N
NC
Br
iPrMgBr,–10 °C
then nPrCHO
OH
N
NC
nPr
Br
Br
3) Provide formal oxidation state, d-electron count and valance lectron count for each of
the following transition metal complexes. If not given, proposed a reasonable
structure.
Me
Ni(COD)2
K2PdCl4
COD =
Ph3P
Cr
(MeCN)2PdCl2
Ph3P
OC
CO
OC
Ph
Me
O
Pd
Br
Ph2P
Pd
PPh2
Co2(CO)8
O
Cp2Ti
Na2Fe(CO)4
Fe
N
Me
Me Me
Me
Me
PPh3
Fe2(CO)9
Me
N
N
Cu-Br
CoCl(PCy3)3
Rh2(OAc)4
OsO4
Me
Me
Cl Ru
Ph
Cl
Me
Pd
PPh3
4) Predict the product for the following reactions. If a single enantiomer of product is
expected, state so, but do not worry about which enantiomer is formed from the
enantiomer of catalyst used. :
Pd2(dba)3
SPhos
K3PO4
Cl
B(OH)2
+
Me
Me
O
Pd2(dba)3
SPhos
NBn
I
I
Pd(PPh3)4
+
SnBu3
H
H
Me
ClMg
Bu
EtO2C
I
+
Ph
B O
O
Pd(PPh3)4
Pd(PPh3)4
+
EtONa
Br
ZnBr
O
NC
Pd(OAc)2/1
NaOtBu
Cl
OTf Me
N
+
PdCl2, PPh3
Et3N
C8H17 NH2
N
O
OAc
N
H
Ph
I
CO2Et
Pd(PPh3)4, NaH
CO2Me
CO2Me
CuI (cat), K3PO4
NHMe
MeHN
(cat)
O
NaCH(CO2Me)2
cat. [Ir(COD)Cl]2
cat 3
OAc
H
PhCCH, 4
Et3N, Zn(OTf)2
Ph
PtBu2
Fe
Me
PCy2
1
CyPF-tBu Josiphos
PCy2
OMe
MeO
SPhos
Me
P N
O
Me
Ph
Me
O
3
NMe2
HO
4
5) Two related reactions from the Grigg group are shown below. A) Please provide a
mechanism for each reaction. B) Rationalize the observed relative stereochemistry
for each transformation by providing 3-D drawings of the possible completing
transition states and providing arguments for why one maybe preferred. C) Finally,
as you will see from the correct mechanisms for each, the order of events differs
greatly with respect to CO in each of these reactions. Please discuss what factors
might influence how and when CO undergoes reaction in these types of cyclizations.
O
10% Pd(OAc)2
20 mol% P(2-furyl)3
CO, NaBPh4
anisole, 120 °C
O
Ph
84%
O
I
TfO
10 mol% Pd(OAc)2
20 mol% PR3
Bu3N, CO
morpholine
1,1-dimethylallene
MeCN, 70 °C
Me
CO2R
Me
O
H
Me
Me
O
N
O
60%
CO2R
For the following questions, please work alone. You may use Reaxys, Scifinder or Web
of Knowledge for these problems.
6) Using Reaxys or Scifinder, please identify up to 3 major US commercial suppliers (ie
Aldrich, Acros, Strem, etc) for each of the following. If fewer suppliers exist, please
state so. (Please see note on the course Syllabus regarding commercial sources).
OMe
Cl
Li
N
iPr
2·BF4
Bu2Mg
N
F
7)
O
MeO
iPr
PCy2
iPr
O
iPr
Please identify at least one paper that provides indicated spectral data in the
specified solvent. the 1H NMR spectra in CDCl3 for the following compounds.
O
PPh3
OMe
1H
in CDCl3
31P
in d6-acetone
8) As you may appreciate, the chemical literature related to organic synthesis dates
back to around 1850, and (as the law of physics have not change significantly since
then) procedures dating back that far can still be very useful. Early organic
chemistry, however, was mostly published in German. One also finds useful
preparations reported in French, Russian, Japanese, etc. A good organic chemist
does not ignore these papers, even if they are not read the language in which they
were published.
As the previous problem points out, Ruppert’s reagent (TMSCF3) and its derivatives
are becoming important reagents in cross-coupling chemistry for preparing
fluorinated organic molecules.
Working alone: Please look up Ruppert’s original procedure for the preparation of
TMSCF3 (Tetrahedron Lett. 1984, 25, 2195). Please give a detailed description of
how the reagents is prepared. Include solvent and temperature, as well as workup
conditions. What yield was reported and what characterization was provided? Report
the NMR data given, and state what reference was used for each spectrum. Also
please describe what side reactions were found in this reaction and what steps were
taken to overcome them.
Please type/chemdraw your answers for this question and hand in the answer
separately from the rest of the problem set. You must work alone for this question,
but you are allowed to use modern language tools, such as dictionaries, BabelFish or
Google Translate. Please see me if you have questions.