Download NAME CHEMISTRY 204 (Spring 1990) Exam III: Chap. 6. (latter part

NAME
CHEMISTRY 204 (Spring 1990)
Exam III: Chap. 6. (latter parts), Chaps. 7, 8, 15: Formation of Alkenes, Alkynes; Reactions of
Alkenes, Alkynes; Preparation of Alcohols; Reactions of Alcohol Derivatives; Ethers: Preparation,
Reactions; Grignard’s; Oxidation; Reduction; Cuprates.
Partial credit will be given when/where appropriate. Brief answers are most welcome, citing specific
experimental support from text or below. Long, rambling answers are not necessary!
Note: There is no particular order to questions presented here. Answer first those questions you know
best. Partial credit will be given when/where appropriate. Brief answers are most welcome, citing
specific experimental support from text or below. Long, rambling answers are not necessary!
Useful Information:
pKa of Acids pKa's of Acids: at 25°: ΔG° = -2.303 RT log K = -1.366 log K (kcals/mole)
H2SO4 -12
CH3SO3-H <0
RNH3+ 10
HI -9
H3PO4 2.2
CH2(CN)2 11.2
HBr -8
HF 3.2
H2O 15.7
HCl -7
CH2(NO2)2 3.6
Alcohols 16-19
H3O+ -1.7
H2S 7.0
(CH3)CO 20
+
HCN 9.1
H-N N <0
R-CCH 25
+
+
H-O R2 <0
NH4 9.2
CH3CN 25
H-S+R2 <0
C6H5OH 9.9
NH3 to R2NH 35-36
alkanes RH 40-60
O
O
C
OH
CH3
4.8
O
C
CH3
O
C
CH2
CH3
O
C
11
CH3
O
CH3
25
Supplies: Common Solvents of all kinds: non-polar; hydroxylic; dipolar, aprotic
Inorganic Reagents, including SOCl2, CO2, Mg, Na, K, Li, Al, NaN3, PX3, CrO3, ZnCl2, D2O, AgBr, AgNO3, RCN,
NaSH, NaOH, NH3, H2SO4, HX (Cl, Br, I), NaSCN, NaH, KSCN, KCN, NaSH, NaOH, NH3, H2SO4, HX(Cl,Br,or I),
NH2OSO3H, I2, Ag2O, Zn(Ag), Zn(Cu), LiX (Cl, Br, I), NaI, NH2OH, NH2-NH2, Raney Ni, Hg+2, CrO3, KMnO4,
H2O2, OsO4, B2H6, ZnCl2, DMSO, HMPT, DMF, (C2H5)3N, CH3CH2NH2, Pd, Pt, CuBr, CuCl, CuCrO4, CrO3
Non-cyclic Organics: one thru five carbon alcohols, H-CC-H, CH3CO2H, , CH3SO2Cl, CH2=O, (C2H5)3N,
(CH3)2SO4, "PCC", CH2=CH-CH2-OH, acids, aldehydes, amines, alkenes, alkynes, ketones, thiols (R-SH); HCC-H, CHCl3, CCl4, CH2=CH-CH2OH, CH2I2, (C2H5)3B, NO, HO-CH2CH2OH, HS-CH2CH2SH, (CH3)3SiCl, CHBr3,
CBr4 CF3CO3H (pertrifluoroacetic acid), CF3-SO2Cl (for "triflates"), CH2=CH-Br, CH2N2, CH2=C=O
Cyclic Organics: Cyclopropanol to Cycloheptanol, C6H5-SO2Cl, pyridine, p-CH3C6H4SO2Cl or
O
CH3
S
Cl
CH2
OH
O
(for "tosylate" prep.),
, CH2 CH2 ,Cyclopropanol to
Cycloheptanol, C6H5SO2Cl, pyridine, C6H5-CH2-OH, C6H5-NH-NH2, m-ClC6H4CO3H ( a per-acid), C6H5-CH2-Br,
C6H5-CO2H, C6H5-CH3, C6H5-C(O)-O-O-C(O)-C6H5 (a peroxide), m-ClC6H4CO3H ( a per-acid),PPh3
Bases (Strong); Reducing Agents: NaH, KH, LiN(-iPr)2 ("LDA"), LiAlH4, NaBH4, CH3Li, KN(SiMe3)2, C6H5-,
LiAlH(O-t-Bu)3
O
1
Conformational Energies for Monosubstituted Cyclohexanes
Group: -ΔG° (axial – equatorial) Kcal mol-1 (25°C)
F 0.25
Cl 0.5
-CN 0.2
-CCH 0.4
-OH 0.5
-CH2CH3 1.8
-OCH3 0.7
CH(CH3)3 2.1
-OTos 0.5
-OC2H5 .0.9
C6H5 3.1
-SH 0.9
-CO2CH3 1.3
Br 0.5
I 0.45
-NH2 1.0
CH3 1.7
C(CH3)3 5-6
1. (06) As you consider the questions that follow, identify an example, if it exists, for each of
the following (give the # of the reaction or where located):
Stereospecific reaction:
Regioselective reaction:
Stereoselective reaction:
2. (10) Outline a synthesis of (I) from the materials on cover, using several reactions/conditions,
including a Grignard reaction. Think Backwards!
CH3
CH2
CH2
CH3
C
OH
CH2
CH3
(I)
2
3. (14) Outline a transformation of (I) into each of the following, using materials on cover. More
than one reaction is involved in each. It would be helpful to show key intermediate products.
No mechanisms needed!
a) Could (II) be an anti-knock additive?
b)
CH3
CH2
CH2
CH3
C
OH
CH2
CH3
(I)
CH2
CH3
CH2
CH3
C
OCH3
CH2
CH3
(II)
b) This transformation does not involve a "rearrangement reaction" as part of the sequence; (I
and (III) are isomers.
CH3
CH2
CH2
CH3
C
OH
CH2
CH3
(I)
CH3
CH2
CH3
CH2
OCH3
CH
CH
CH3
(III)
3
4. (10) In contrast to 3(b), when (III) is treated as shown, (I) is obtained in one reaction! Draw a
mechanism for this reaction:
CH3
OCH3
CH2
CH3
C
OH
CH2
CH3
H2SO4 dil
CH
CH3
CH2
CH
CH3
CH3
CH2
H2O / 0
CH2
(III)
(I)
5. (15) Recently (Tet. Letts. 31, 973 (1990) the following was described.
+
H
SeF
SePh
H
H
F
+
H
SePh
F
H
H
(PhSeF)
a) Write a mechanism that accounts for one of the observed products.
4
b) Based on your answer in (a) plus class discussion, predict the structures (including
stereochemistry) of the two stereoisomeric products expected when (IV) is treated with
[PhSeF]. Include the structure of the key reaction intermediate and point out (discuss) the
feature that makes only two products possible.
+
H
SeF
CH3
(PhSeF)
(IV)
6. (25) Complete each of the following sequences of reactions, either indicating the
reagents/conditions, in order if necessary, or drawing the structure(s) of the organic product(s)
expected. Where stereochemistry is important, so indicate.

1. BH3 / O
a) (05)
C2H5
C
C
C2H5
O
3 moles alkyne/BH3
H3C
C
OD
1. Hg(OAc)2 / CH3OH
etc.
partial structure
H
2. NaBH4 / OH74% of
b) (05)
5
CH3
c) (08)
CH3
CH2
CH2
C
CH3
CH2
Br
Think Backward!
CH3
H
CH3CH2
CH3
CH2
CH2
C
CH3
CH2
O
CH2
C
OH
CH2CH2CH3
C
C
H
d) (07)
Figure "mode" of addition 1st!
H
CH2CH2CH3
C
CH3CH2
HO
C
H
OH
and enantiomer
6
7.(18) Several years ago some Swiss chemists described a synthesis of certain cyclic esters
thought to have biological activity(Chem. Common., 1513(1987)).
a) A portion of the synthetic scheme is shown below; complete each step with appropriate
reagent(s), in order if needed, using materials from the cover page. Please include critical
reaction conditions, if needed.
H
C
C
(CH2)2
H
O
H
-C5H11
CO2H
C
(CH2)2
CO2H
H
H
C
C
C
C
(CH2)2
-C5H11
CO2H
C
(CH2)2
-C5H11
CO2H
(V)
(VI)
b) How would (V) be transformed into (VII)?
H
CH2
H
C
H
C
(CH2)2
-C5H11
(V)
CO2H
H
C
C
(CH2)2
-C5H11
(VII)
7
CO2H
8.(13) Given a large sample of (VIII), outline transformations of it into (IX) and (X) with as high a.
degree of optical purity in the product of each step. Use available reagents, and draw structures
of any isolated intermediates in each transformation. You will need at least two reactions on
each route.
H
I
C
C2H5
CH(CH3)2
H
(IX
C2H5
C
OH
(CH3)2CH
(VIII)
H
C2H5
C
C
N
(CH3)2CH
(X)
9).(12) Lithium dialkylcuprates are also considered organometallics, as are Grignard reagents.
Illustrate usage of R2CuLi by outlining a synthesis of (XI) from available materials on cover.
THINK BACKWARDS)
CH3
CH
C2H5
(XI)
8
10.(06) Outline a mechanism for the following reaction, in which a limited amount of HI has
been used.

(CH3)2CH-O-CH(CH3)2
+
HI
(CH3)2CH-I
+
(CH3)2CH-OH
11.(13) (a) Ozonolysis of a sample of alkene, C8H14, gave equal moles of (XII) and (XII). Draw the
structure of one possible alkene, representing the substituent’s at the double bond in 3dimensions as much as possible.
O
1. O3
C8H14
O
2. Zn / H2O
+
CH3
C
H
CH3
b) When your alkene in (a) is treated with HBr, only one product appears. Draw that product as
well as the key intermediate leading to it.
c) Draw an epoxide of the alkene from (a), then allow it to react with concentrated NH3. Draw
the structure of the resulting product, including the stereochemistry.
NH3

9