Baran Group Meeting
JOC Year in Review: 1994
Statistics:
Volume 59
Issues 1-26
8315 pages
Top 5 Most Cited Papers:
Publication Record:
Marshall, J A (13)
Adam, W (10)
Paquette, L A (10)
Denmark, S E (9)
Katritzky, A R (8)
Padwa, A (8)
Rapoport, H (8)
Brown, H C (6)
Danishefsky, S J (6)
de Kimpe, N (5)
Leah Simke
Ishii, Y (5)
Kumar, A (5)
Kurth, M J (5)
Liebeskind, L S (5)
Matsumoto, K (5)
Miller, M J (5)
Mori, M (5)
Pettit, G R (5)
Rozen, S (5)
Sato, Y (5)
Notable Events of 1994:
Jan 1st - AAPL was $1.04
Jan 10th - Lorena Bobbitt's trial begins
Mar 31st - Nature reports the finding in Ethiopia of the first complete
Australopithecus afarensis skull
Apr 7th - Vatican acknowledges Holocaust for 1st time
Apr 22nd - In Denmark the largest lollipop, weighing 3,011 pounds, made
May 10th - Nelson Mandela sworn in as South Africa's 1st black president
Jun 15th - Ruth Bader Ginsburg, sworn in as Supreme Court Justice
Jun 26th - 126°F (52.2°C) in Death Valley, Calif
Nov 9th - The chemical element Darmstadtium is discovered.
A Practical Method for the Large-Scale Preparation of [N,N'-Bis(3,5-ditertbutylsalicylidene)-1,2-cyclohexanediaminato(2-)]manganese(III)
chloride, a Highly Enantioselective Epoxidation Catalyst
Jay F. Larrow, Eric N. Jacobsen, Yun Gao, Yaping Hong, Xiaoyi Nie,
Charles M. Zepp
642 citations
On the Nature of the "Copper Effect" in the Stille Cross-Coupling
Vittorio Farina, Suresh Kapadia, Bala Krishnan, Chenjie Wang, Lanny S.
Liebeskind
395 citations
Lanthanide Triflates as Water-Tolerant Lewis Acids. Activation of
Commercial Formaldehyde Solution and Use in the Aldol Reaction of
Silyl Enol Ethers with Aldehydes in Aqueous Media
Shu Kobayashi, Iwao Hachiya
345 citations
Acceleration of the Dess-Martin Oxidation by Water
Stephanie D. Meyer, Stuart L. Schreiber
328 citations
Cationic BINAP-Ru(II) Halide Complexes: Highly Efficient Catalysts
for Stereoselective Asymmetric Hydrogenation of .alpha.- and .beta.Functionalized Ketones
Kazushi Mashima, Koh-hei Kusano, Naomasa Sato, Yoh-ichi Matsumura,
Kyoko Nozaki, Hidenori Kumobayashi, Noboru Sayo, Yoji Hori, Takero
Ishizaki
288 citations
Top Songs:
The Sign by Ace of Base
I Swear by All-4-One
I'll Make Love To You by Boyz II Men
Top Movies:
The Shawshank Redemption
Pulp Fiction
Forrest Gump
Page 1
JOC Year in Review: 1994
Baran Group Meeting
Leah Simke
Select Natural Products Isolated
Pentalenene
104, Burnell
O
(CH2OH)2
p-TsOH
Me
N
H
curacin A
S
O
O
OH
O
OMe
TMSO
Me
H
Me
Me
Me
Me
Me
Et
Et
OTMS
BF3•Et2O
O
O
mech.?
Me
Me
Et
OO
H Et
Me
Me
+ diast.
O
H
O
KOtBu
O
(−)-prehalenaquinone
H
H
Me
Me
Me
Me
Me
H
Me
3 steps
O
H
+ diast.
Me
Me
H
pentalenene
O
N
NH H
O
H
Me
4 steps
N
N
O
O
O
NH
HN
NH
OH
HO
O
O
MeN
Me
N
O
Me
O
I
O Me
Me
N
H
HO
Me
OH
Me
Me
O
CC-1065 (protected A unit)
192, Tietze
H2N
Me
OH
Me
"...we have become interested in highly toxic
compounds which can be detoxified by the
formation of derivatives which may be cleaved at
pH 6.2 with liberation of the toxin."
doliculide
O
N
H
- first synthesized by Boger et al. (1992)
- cancer tissue pH ~6.2; normal tissue pH ~7.2
HN
OMe
NH
N
N
O
O
O
phakellistatin 3
N
H
OH
C
OMe
B
A
Me
HO
O
Me
H
OH N
H H
Me
H
NH
N
MeO
OH
O
Br
Me
HO Me
heliannuol B
OH O
H
bioxalomycin α1
O
O
NH2 1. PhSO2Cl/py
OBn
Cp Cp
H3C Zr
Br
2. NaH,
allyl bromide
N
N
SO2Ph
SO2Ph tBuLi,
Cp2Zr(CH3)Cl
OBn
Cp
Cp Zr
N
SO2Ph
-CH4
OBn
OBn
O
I
O O
O
6 steps
Sch 49209
I
N
SO2Ph
OBn
10% byproduct
(can be recycled)
N SO Ph
2
I
OBn
I2
Cp
Cp Zr
N SO Ph
2
OBn
45%
Page 2
JOC Year in Review: 1994
Baran Group Meeting
OAc
OAc
N
I
SO2Ph
Heck Rxn
N
Ac
OBn
SO2Ph Me
N
N
Ac
OBn
A
SO2Ph
Me
N
SO2Ph
AA
A
Me
Me
BuLi
O
O
HO
H
Me
H
H
Me
H
O
HO
H
70:30
O
Me
Me
O
O
then
3 steps
O
Me
OMEM
Me OH
2 steps
Me
O
Me
H
O
OH
Me
Me
O
3 steps
HO
H
H
O
Me
O
AD-mix-α
O
OH
H
H
C
Me
O
Me
AD-mix regioselectivity:
Once A is dihydroxylated,
B is much less reactive than C
Pseudopterane 2,5-Furanocyclic Ring System
324, Marshall
Me
most
reactive
B
2. (CH3)2C(OMe)2
equally
reactive
O
see Boger et al.
JACS, 1988, 4796.
30%
70%
Me
O
A
1. AD-mix-β
N
H
OBn
B
64%
10%
a. Pd(OAc)2, NaOAc, NBu4Cl, DMF
b. Pd(PPh3)4, NEt3, CH3CN
Aspicilin
949, Sinha and Keinan
OAc
N
a or b
N
Ac
Leah Simke
O
3 steps
OAc
OH
Me
O
Me
3 steps
O
OMEM
Me
Me O
Me
Me
O
EtO2C
(+)-aspicilin
Me
O
OMEM
EtO2C
trans-isomer
MnO2
Me
Me
Me
BuLi
O
O
HO
H
Me
Me
H
Me
Me
OH
O
Examples:
O
HO
O
Me
Me
O Kallolide A
"Key Reactions":
Core Ring System of the Cyathins
885, Paquette
S
O
hv
O
120º C,
cat. Et3N
S
Me
O
5 Steps
OH
S
KH
18-cr-6;
MeO
Cl
HCl
S
S
H
Cl
MeLi
O
via:
S
S
R
R
R
R
Base-induced cleavage
O
O
O
OH
Synthesis of inverse demand Diels-Alder coupling partner:
SH
O
HO
CHR2
O
O
SH
R
Intramolecular Paterno-Büchi
NH4Cl,
H2O
Me
O
Me
O
Me
OMe
base
O
O
O
S
"In these cases, not only the possible interactions but also
the beauty of the molecules1 initiated our studies."
OH
O
cis-isomer
E (40%)
Z (60%)
"Stellatrienes"
1027, Gleiter
Previous strategy:
Me
Me
Me
OH
Me
Me
1J. Aestetics Art
Criticism 1990, 48, 191.
Page 3
JOC Year in Review: 1994
Baran Group Meeting
Leah Simke
Et
O
Cl
ClCO2Et
•
[4+2]
hv
DATMP
N
CO2Et
HO
O
name?
O
Et
1. (COCl)2,
DMSO
2. Et3N
MsCl,
Et3N
iPrLi
HO
Et
Ms2O
KOtBu
N
Ms
N
O
N
Ms
Tf2O
A
X
A
R'
R
Co2(CO)8
B
NaBH4,
CeCl3
O
B
N
Tf
Me
X
R
A
A
Bu3SnH
B
NO2
O2N
OH
H
H
NO2
O
Ph
OH
H
O
O
O
H
O
Ph
Me
Ph
O
AcN
H
H
NO2
NO2
O2N
NO2
1
1. HOAc
HO
OH
NH2
2. HBr, HOAc
3. KOH
TNT
1.69
1.66
1.65
Me
NO2
O2N
Me
NO2
HNO3
HOAc/
Ac2OH
NH2
NO2
H2SO4
H2S2O8
O2N
NHNO2
O2N
name?
Et
Et
ONO2
Et
4 steps
Et
NH2
Me
O2N
Me
NO2
NO2
3 steps
O2N
NH2
O2N
NO2
NO2
Me
ONOSO3H
H2SO4
O2N
N2
O2N
NO2
H3PO2
NO2
ONO2
ONO2
N
N
NO2
ONO2
N
NO
N
H2
Et
N
NO2
NO2
1
N2O4
(various
conditions)
N
NO2
2
2-Azetines
1608, Marchand, Bott, and Archibald
Et
NO2
3
Me
OH
H
no NaBH4/CeCl3;
trans pdt observed
O2N
all slightly more dense than TNT due to presence of additional nitro group
Ph
OH
1.70
NO2
O2N
NO2
1
density
(g/mL):
Me
Me
O2N
NO2
A or B = heteroatom; X = Br or SePh; R' = Me or H
Me
N
Tf
Me
R
B
OH
H
Ph
not formed
NOH
Tetranitrotoluenes
1714, Nielson and Wilson
General Scheme:
X
R
N
Ms
NH2OH
O3
N
Tf
Angularly Fused Triquinanes
1396, Clive
favored by
12 kcal/mol
O
ClCO 2 Et
ClCO 2 Et
Me
Et
OMs
Et
N
NO
Page 4
JOC Year in Review: 1994
Baran Group Meeting
Sophoradiol
2324, Johnson
CN
MgBr
F
F
MgBr2
O
Strychnine
2685, Rawal
"...first examples of nonenzymic, biomimetic polyene pentacyclizations..."
Me
F
Leah Simke
TMS
Br
Me
CO2Et
TMS
CO2Et
K2CO3
1. Pd(OAc)2,
Bu4NCl,
K2CO3
2. HCl
N
H
OH
H
•
H
H
H
H
OH
HO
H
Rubrolone C Ring
3453, Boger
Br Br
Sophoradiol
N H
CO2Me
O
Et3N
O
H
H
O
O
strychnine
O
Br
H
N
O
isostrychnine
3 steps
F
TMS
controls D/E
cis-syn
configuration
N
"ethanolic
potash"
N H
TFA
CO2Me
MeOH
quench, Δ
N H
O
terminates
cyclization
F
TMS-I;
OTBS
O
CO2Et
Me
HO Me
I
tBuOK
controls
regiochem
Br
N
CO2Me
N
H
N
N H
TMS
CO2Me
OTBS
F
MeLi
185 ºC
N
MeO2C
then ClCO2Me,
PhNEt2
I
Me
LDA
F
N CO2Me
Me
NH2
TMS
HO
CHO
N CO2Me
5 steps
NO2
TMS
H
MeO2C
O
CuCNLi2
2
O
Br
O
O
O
DBU
O
O
Me
Me
1. NBS, H2O
2. KOtBu
Me
O H
O
H
H O
H
O
O
This space is intentionally left blank.
O
OH
O
O
O
Me
O
25 ºC, 15 min
O
H
H
exo transition state
Me Me
O
O
O
Me
Me
O
O
OH
HO
2.NBS,
Ph3P HO
3. Zn,
NH4Cl
HO
OH
1. LiOH
O
MnO2
OH
O
O
Page 5
JOC Year in Review: 1994
Baran Group Meeting
Leah Simke
Cyclic Enol Ethers via Mo RCM
4029, Grubbs
Molybdenum Catalyst
General Scheme:
OR1
R1
OR1
n
OR1
n
i-Pr
N
n
O
R1
n
O
O
R1
n
O Me
H
N
SBn
H
N
N
Me H
SBn
Cbz
i-Pr
Ph
Me
RO Mo
RO
R2
O
R1
SBn
R2
O
n
Thiangazole
4733, Heathcock
CO2Me
O Me
H
N
Ph
O
O
O
Ph
O
NH
Me
N
Ph
O
O
O
O
DMP
N
S
Me
OH
O
HO
OH
O
O
O
CO2Me
CH3CHBr2,
TiCl4, Zn,
O
O
7 steps
OR
R = CH2Ph
Me
HO
O
O
RO
OH
O
H2, Pd/C
O
O
RO
OR
12 mol %
[Mo] cat.
O
S
Me
N
DDQ
S
Ph
(− )-thiangazole
OLi
N
OMe
MeO2C
O
Et
1. CeCl3
2. Et
N
O
3. H3O
Br
O
N
O
N
N
Br
OMe
O
O
Et
HO
O
1N HCl
Et
HO
O
O
O
HO Et
N
OH
(i-PrO)3Al
OH
CO2Me
HO Et
Me
S
Me
N
S
N Me
N CHO
Me
Me
S
Me
N
Ph
Li
N
N
S
Me
OR
O
Me
N
N
Me Me
N
OMe 2. Me N
Me
3. n-BuLi
Pd(OAc)2
O
O
N
72%
N
O
O
Me
N
p-TsOH
Me
MeHN
−n I
1. MesLi
TMEDA,
cat. PbCl2
Me
Ph
Camptothecin
5120, Comins
Benzofuran NP Synthesis:
O
S
Me
S
Ph
NHMe
H3N
O
O
S
Me
N
OBn
O
N
S
RO
CO2H
Me
SBn
Cl
NHMe
MeHN
NH
Me
O
S
Me
N
n-Pr
Ph
O
OBn
N
Me H
SBn
O
MeHN
N
Ph
O
Me
O
Me
OH
Some Products:
Ph
H
N
Me
H
N
N
Me H
SBn
Me
Ph
O Me
N
Me H
SBn
O
SBn
MeHN
O
Ph
Me
SBn
O
R = CMe(CF3)2
1. Na, NH3
2. NH4Cl
3. TiCl2
O
H
N
Me
= H, Me; n = 1,2
Ph
3 steps
N
H
O
N
OMe
O
(±)-camptothecin O
Page 6
JOC Year in Review: 1994
Baran Group Meeting
Leah Simke
Silphiperfol-6-ene and Methyl Cantabradienate
5419, Snider
Me
Me
Me
1. PDC
2. (COCl)2
MgBr
O
N
CHO
Grayanotoxin III
5532, Matsuda and Shirahama
Me
Me
Me
Me
Cl
CHO
Ot-Bu
Me
Me
H
Mn(pic)3
Me
H
Li
Me
H
HO
Me
Me
O
•
O
O
Me
H
Na,
NH3/EtOH
MeLi
Me
HO Me
Me
KHMDS,
PhN(Tf)2
H
MeO2C
H
NaAuCl4•H2O
O
O
SPh
H
O
1. n-BuLi
Me
10 steps
O
OH
Me
OR
Me
H
O
OR
Me
Me
Me
4 steps
OH
O
OH
O
SPh
H
MPMO
OH
H
OR
Me
O
HO Me
SmI2
Me
Me
TBDMSO
OR
O
OH
Me
SPh
H
H
O
3 steps
Me
Me
H
O
O
Me
Me
H
O
SmI2
R = MOM
Me
silphiperfol-6-ene
H
H
BnO
OMPM
Me
Me
H
Me
OTMS
2. 10% HF
3. PDC
MeO2C
2. (PhS)2
Me
1. Δ,
BnO
OH
DMAP,
Et(i-Pr)2N
[2+2]
Me
Me
TsO
O
t-Bu
Me
Me
6 steps
OR
OR
Me
1. [Pd], CO
Me 2. CH2N2
TfO
Me
Me OR H
H
MeO2C
HO
SmI2
methyl cantabradienate
7 steps
Me
Me
This space is intentionally left blank.
Me OR
H
H
3 steps
Me
Me HO
OR
OH
OR
Me
OR
O
O
HO
H
H
OR
HO
H
TBDMSO
Me
Me
OR
MeOH
OR
Me
HMe OH
H
Me
Me HO
OH
Me
OH
(−)-grayanotoxin III
OH
Page 7
JOC Year in Review: 1994
Baran Group Meeting
Illudin M
6965, Kinder
Leah Simke
O
Me
Me
O
O
N2
Me
Me
Me
O
Br
Rh2(OAc)4
Me
O
Me
Me
O
Me
HO
Me
OH
Me
Me
Me
O
HO
Br
NBS
pyridine
O
MeMgBr
KOH/MeOH
Me
Br
Me
O
HO
Me
Me
OH
Me
O
O
Me
Me CrO3/H2SO4
LAH
HO
Me
Me
OH
OMe
LAH
Me
HO
Me
Me
OH
Me
Me
O
O
Me
HO
Me
Me
OH
(±)-illudin M
Also, taxol.
Page 8