Quinone-cyclized porfiromycins

Article abstract of DOI:10.3987/com-01-9215

Mitomycin C and porfiromycin cyclization has been implicated in the pathway for KW-2149 and BMS-181174 function. The importance of the porfiromycin C(7) structure and nucleophile for quinone cyclization was determined showing that both C(7) and C(8) annul

Full text of DOI:10.3987/com-01-9215

HETEROCYCLES, Vol. 55, No. 7, 2001, pp. 1347 - 1364, Received, 2nd April, 2001
QUINONE-CYCLIZED PORFIROMYCINS
Younghwa Naa and Harold Kohnb*
a Department of Chemistry,
University of Houston,
Houston, Texas 77204-5641, USA
b Division of Medicinal Chemistry and Natural Products,
School of Pharmacy,
University of North Carolina,
Chapel Hill, NC 27599-7360, USA
Abstract – Mitomycin C and porfiromycin cyclization has been implicated in
the pathway for KW-2149 and BMS-181174 function. The importance of the
porfiromycin C(7) structure and nucleophile for quinone cyclization was
determined showing that both C(7) and C(8) annulation processes occur.
Mitomycin C (1) is extensively used in cancer chemotherapy1 and serves as the prototypical bioreductive
alkylating agent.2 Since its clinical introduction over 600 semi-synthetic mitomycin analogues have been
prepared in an effort to identify more efficacious agents.3 In recent years, two mitomycins, KW-21494,5
(2) and BMS-1811746,7 (3), have attracted extensive attention. Both compounds have undergone clinical
trials, and 2 advanced to Phase II testing.8
O
O
CH2OC(O)NH2
OCH3
CH2OC(O)NH2
OCH3
RS(CH2)2(H)N
CH3
H2N
CH3
8
7
N
NH
N
NH
6
O
O
2 KW-2149
R = -S(CH2)2N(H)C(O)(CH2)2CH(NH2)CO2H
1
3 BMS-181174 R =
4 R = H
S
NO2

Speculation exists as to the function of 2 and 3. Structurally, they have much in common with 1. Only
the C(7) substituent in 1-3 differ; in 1, the C(7) moiety is an amino unit while in 2 and 3 it is an
aminoethylene disulfide group. The mechanisms proposed for 2 and 3 function are different than 1.5f,k,9-11
These pathways suggest that external thiol-mediated (e.g., glutathione, serum albumin) disulfide cleavage
of the C(7) aminoethylene disulfide unit is instrumental for drug function. In several reports, 7-N-(2'-
mercaptoethyl)mitomycin C (4) has been proposed as the key intermediate, and suggestions have been
made that this thiol undergoes quinone cyclization at the C(6), C(7) or C(8) sites to generate the
intermediate cyclized adducts (5-7) (Figure 1).9-11 In 1999, Wang and Kohn reported HPLC profiles for
reactions designed to generate 4 and the corresponding porfiromycin thiol (8).11 Porfiromycin (9) is an
analogue of mitomycin C (1) in which the N(1a) hydrogen has been replaced with a methyl moiety.2 The
chromatograms for these reactions showed multiple peaks, which upon addition of thiol trapping reagents
produced a single, major adduct corresponding to the modified thiol. These findings were consistent with
the notion that thiols (4) and (8) cyclized at one or more sites to give an equilibrium isomeric mixture.11
Attempts to characterize these adducts were unsuccessful.
Figure 1.
Origin of Multiple HPLC Peaks
SH
O
CH2OC(O)NH2
OCH3
7
N
H
8
N
NH
CH3
6
O
4
O
O
S
CH2OC(O)NH2
OCH3
CH2OC(O)NH2
OCH3
CH2OC(O)NH2
OCH3
OH
H
N
H
S
HN
N
H
CH3
N
NH
N
NH
N
NH
S
CH3
H
CH
3O
O
O
C(6)
C(7)
C(8)
5
6
7

O
O
CH2OC(O)NH2
OCH3
X
NCH3
N
CH3
8 X = N(H)CH2CH2SH
9 X = NH2
15 X = OCH3
In this study, we report the synthesis and chemical properties of novel mitomycins designed to undergo
quinone cyclization. We show that cyclization can proceed at the quinone C(7) and C(8) sites, and that
cyclization depends upon the structure of the C(7) substituent.
RESULTS AND DISCUSSION
A.
Selection of Compounds
In this study we asked whether nucleophiles tethered at the C(7) porfiromycin site cyclize to give C(6),
C(7) and C(8) adducts (Figure 1). We prepared two porfiromycin series (Figure 2: A and B).
Figure 2.
Substituted Porfiromycins
O
O
CH2OC(O)NH2
OCH3
X
N
NCH3
CH3
Series B
Series A
YH
YH
N
X =
X =
N(H)
Y = O, S
Y = O, NH, S
Porfiromycin analogues, rather than mitomycin derivatives, were synthesized to prevent N(1a)-C(5a)
cyclization processes.12 Series A contained a C(7)-substituted cyclohexylamino unit, and series B had a
C(7)-substituted piperidino moiety. In both series, we maintained a two-carbon (C2) bridge between the
C(7) amino unit and the terminal nucleophile. We retained this structural factor since a similar spatial
relationship existed in 2 and 3.13 Structural analogues of 2 and 3 with linkers longer than C2 were less
cytotoxic than 2 and 3.13 Furthermore, we expected that a C2 bridge would entropically promote ring
cyclization. The C(7)-piperidino unit in B (Figure 2) distinguished this set of compounds from the
corresponding C(7)-amino units in series A compounds and 1-3. Structural models predicted that C(7)-
piperidino steric interactions with the C(6)-methyl moiety would result in the loss of resonance

interactions of the C(7)-piperidino nitrogen with the C(7)-C(6)-C(5)-O(5) conjugated system and decrease
the electron density within the quinone system (Figure 3).
Figure 3.
Potential Steric Interactions in C(7)-Piperidinoporfiromycins Promoting Quinone
Cyclization
..
XH
CH2X
O
O
O
O
.
N
?
..
.
N
N
7
X CH2
6
CH3
CH3
CH3
5
O
O
This notion is supported by the reported quinone reduction potentials for 1 (E = -0.45 V) and 7-
½
piperidinomitomycin14 (10) (E = -0.27 V),15 indicating that 10 is more readily converted into the
½
corresponding hydroquinone than is 1. We also expected that the loss of planarity of the C(7) piperidino-
substituent with the quinone system would facilitate cyclization processes (Figure 3).
O
CH2OC(O)NH2
N
OCH3
N
NH
CH3
O
10
B.
Series A Porfiromycins
The series A 2'-amino C(7)-cyclohexylaminoporiformycins (11-14) were the first compounds slated for
synthesis. In 1989, Kyowa Hakko Kogyo scientists reported coupling a diastereomeric 1,2-
diaminocyclohexane mixture with mitomycin F (15).16 The product mixture was not separated but was
assigned as C(8)-imino porfiromycins (16-19). We were anxious to learn if C(8) cyclization depended
upon cyclohexane diamine geometry. Beginning with enantiomerically pure (1S, 2S)-trans- (20) and (1R,
2R)-trans-(21) 1,2-diaminocyclohexanes, condensation with 15 in MeOH gave C(8)-iminoporfiromycins
(16) and (17), respectively. Similarly, treatment of 15 with cis-1,2-diaminocyclohexane (22) gave 1817
and 1917 as an 1:1 diastereomeric mixture (HPLC, TLC analyses). The spectral data for 16-19 were in
agreement with the proposed structures, showing that imine formation was favored irrespective of cyclo-
hexanediamine geometry. In particular, we observed for imines (16-19) a molecular ion peak in the low-
and high-resolution MS. In the 13C NMR for 16 and 17, a single carbonyl peak (~179 ppm) was detected
along with an additional downfield signal at ~153 ppm. The peak at ~153 ppm was diagnostic for the
C(8) imine carbon.10,18

2'
1'
NH2
2'
O
O
N
O
CH2OC(O)NH2
OCH3
CH2OC(O)NH2
OCH3
1'
N
N
H
H
N
NCH3
N
NCH3
CH3
CH3
11 1'(S), 2'(S)
12 1'(R), 2'(R)
13 1'(S), 2'(R)
14 1'(R), 2'(S)
16 1'(S), 2'(S)
17 1'(R), 2'(R)
18 1'(S), 2'(R)
19 1'(R), 2'(S)
2
1
NH2
NH2
NH2
NH2
22
20 1(S), 2(S)
21 1(R), 2(R)
Our findings documented that the quinone C(8) site was prone to nucleophilic modification, a finding in
agreement with earlier reports that mitomycins containing a C(7) acyclic terminal amino substituent
underwent C(8) imine formation.10,16,18
The second set of series A compounds consisted of compounds (23-26). We prepared porfiromycins
(23)17 and (24)17 by treating 15 with commercially available trans-2-aminocyclohexanol·HCl (27) and
triethylamine in MeOH. Using the same procedure, we prepared 2517 and 2617 from 15 and cis-2-
aminocyclohexanol·HCl (28).19 The diastereomeric porfiromycins (23-26) were separated by PTLC. The
low- and high-resolution MS spectra for 23-26 exhibited a molecular ion peak ([M+1]+). The 13C NMR
spectra for 23-26 showed chemical shifts for the quinone ring system comparable to 9,20 documenting that
the 2' hydroxyl unit did not cyclize at any of the quinone ring sites.
2'
OH
2
OH
O
CH2OC(O)NH2
N
H
1'
OCH3
NH2
1
N
NCH3
CH3
O
27 1(S),2(S) + 1(R),2(R)
28 1(S),2(R) + 1(R),2(S)
23 1'(S), 2'(S)
24 1'(R), 2'(R)
25 1'(S), 2'(R)
26 1'(R), 2'(S)

We then attempted to learn if (29) would undergo quinone cyclization. Replacement of the alcoholic
residue in 23-26 with the nucleophilic thiol unit should foster cyclization. Unfortunately, attempts to
prepare porfiromycins (29) using a diastereomeric mixture of cis- and trans-2-
aminocyclohexanethiol·HI21 (30) and 15 in basic MeOH were unsuccessful. Under deaerated conditions,
we obtained only disulfides (31) and (32). High-resolution MS spectroscopy (CI) of the mixture showed
signals at 592.262 27 ([M+1]+) and 922.372 97 ([M]+) corresponding to the molecular ion peaks of 31 and
32, respectively. We verified this finding by preparing disulfide (33) from 30 and H2O2 and then treating
the disulfide mixture with 15 in basic MeOH to give 31 and 32 (data not shown). The origin of 31 and 32
has not been determined. We suspect that 30 oxidatively dimerized to 33 under the reaction conditions
and then 33 reacted with 15 to give 31 and 32. A similar finding has been reported by Kono and
coworkers for the reaction of mitomycin A with cysteamine.13
2'
SH
O
CH2OC(O)NH2
N
H
SH
1'
OCH3
.
N
NCH3
CH3
NH2 HI
O
29
30
O
O
CH2OC(O)NH2
OCH3
H2N
S
S
N
H
NCH3
N
CH3
31
O
O
O
O
CH2OC(O)NH2
OCH3
H2N(O)COCH2
CH3O
N
H
S
S
N
H
N
NCH3
CH3N
N
CH3
CH3
32
S
S
R
R
.
33 R = NH2 HI

B.
Series B Porfiromycins
Series B porfiromycins consisted of 34-37. We envisioned that treatment of 15 with commercially
available (S,R)-2-piperidinemethanol (38) would initially provide 34 and 35.
YH
2'
O
CH2OC(O)NH2
OCH3
Y
2
N
NH
N
NCH3
CH3
O
38 Y = OH, 2(S) + 2(R)
46 Y = SH, 2(S) + 2(R)
34 Y = O, 2'(S)
35 Y = O, 2'(R)
36 Y = S, 2'(S)
37 Y = S, 2'(R)
2(S) + 2(R)
52 Y =
S
S
N
,
NO2
N
When both compounds were mixed in MeOH, we observed the rapid disappearance of 15 and the
appearance of two major orange products (HPLC and TLC analyses). PTLC separation of the mixture
provided 3917 and 4017 (43% isolated yield). Spectroscopic studies documented that these compounds
were C(7)-N,O-spiro adducts. We observed molecular ion peaks in the low- and high-resolution MS
spectrum for 39 and 40. In the 1H NMR spectrum, the C(6) methyl protons appeared as an upfield doublet
(~δ 1.31) and was coupled to the downfield C(6) methine quartet (~δ 3.34). Further structural support
came from the 13C NMR spectrum. First, the resonances for C(6) and C(7) appeared at ~52.0 ppm and
~97.8 ppm, upfield of the corresponding 105.1 and 147.3 ppm peaks for 9. Second, the piperidino C(2')
methylene carbon resonated ~10 ppm downfield of the corresponding signal in 38. Finally, the quinone
carbonyl carbon signals (191.7-193.4 ppm) appeared downfield (~15 ppm) of those in 9.
O
O
CH2OC(O)NH2
OCH3
CH2OC(O)NH2
OCH3
O
N
7
7
N
6
O
CH3
6
N
NCH3
N
NCH3
CH3
H
H
O
O
40
39
The observation of only two major products from the reaction of 38 with 15 (HPLC analysis) was
surprising and indicated that C(7) spiro-cyclization proceeded with a high degree of stereospecificity.
Cyclization introduced new stereocenters at C(6) and C(7). The isolation of 39 and 40 demonstrated that
appropriate nucleophiles tethered at the porfiromycin C(7) position can react at the C(7) site to give

quinone cyclized adducts. A comparable product was reported by Kasai and coworkers, who prepared the
C(7) cyclized 41 adduct in which both C(7) heteroatoms were oxygen.22
O
CH2OC(O)NH2
O
OCH3
7
O
CH3
N
NCH3
H
O
41
The generality of this C(7) spiro-cyclization reaction was briefly explored. Treatment of 15 with (S)-(42)-
and (R)-(43)-pyrrolidinemethanol in MeOH led to the rapid production of 44 and 45, respectively. The
spectral properties for 44 and 45 documented C(7) pyrrolidinemethanol substitution and that C(7)
modification proceeded without spiro-cyclization.
OH
OH
2
O
2'
CH2OC(O)NH2
OCH3
NH
N
N
NCH3
CH3
O
42 2(S)
43 2(R)
44 2'(S)
45 2'(R)
We next attempted to synthesize 36 and 37 using (S,R)-2-piperidinemethanethiol (46) and 15. We
prepared 46 as the hydroiodide salt from 38 using an improved procedure (Scheme 1). (S,R)-2-
Piperidinemethanol (38) was protected as the (N)-t-Boc derivative (47)23 and then treated with DEAD,
PPh3 and thiolacetic acid to give the Mitsunobu-coupled product (48). Hydrolysis of thioacetate moiety in
48 gave 49; removal of the t-Boc group with trimethylsilyl iodide provided 46 in 56% overall yield from
38.
Scheme 1.
Synthesis of 2-Piperidinemethanethiol Hydrogen Iodide (46)
SR'
OH
NR
NR
b
38 R = H
47 R = C(O)OC(CH3)3
48 R = C(O)OC(CH3)3, R' = C(O)CH3
49 R = C(O)OC(CH3)3, R' = H
a
c
d
46 R = H, HI, R' = H
a, t-Boc anhydride, THF, 85%; b, PPh3, DEAD, CH3C(O)SH, 71%;
c, K2CO3, CH3OH-H2O, 93%, d, TMSI, CDCl3, 99%.
Addition of 46 to 15 in the presence of K2CO3 and triethylamine in a deaerated (Ar) methanolic solution
led to the rapid formation of N(1a)-methyl-7-methoxyaziridinomitosene24 (50) as the major product
(HPLC and TLC analyses). Compound (50) has been prepared from 15 by a sequential reduction-

oxidation route.24 We suspect a similar process occurred in this transformation. Previous reports have
documented that thiols can reduce mitomycin A (51).13 Two additional findings supported this notion.
First, repetition of the reaction in non-deaerated methanolic solutions showed little reaction for extended
time periods (2 d) (HPLC analysis). Second, treatment of 15 with the 4-pyridyl (52) and 5-nitro-2-
pydridyl (53) disulfide analogues of 46 in non-deaerated basic MeOH solutions produced little product
and the recovery of 15 (data not shown).25
O
O
CH2OC(O)NH2
CH2OC(O)NH2
OCH3
CH3O
CH3
CH3O
CH3
N
NCH3
N
NH
O
O
50
51
CONCLUSIONS
Our findings document that nucleophiles appended to the quinone ring within the porfiromycin skeleton
can generate C(7)- and C(8)-modified adducts. These results suggest that the multiple peaks observed
upon generation of thiols (4) and (8) likely resulted from quinone modification. The pharmacological
ramifications of these cyclization processes and whether these transformations contribute to drug efficacy
are topics of current investigation.
EXPERIMENTAL
General Methods. UV-visible spectra were obtained using a Cary-3Bio UV-visible spectrophotometer.
1H NMR and 13C NMR spectra were taken on General Electric QE 300 MHz and Bruker AMX 600 MHz
NMR instruments. Low-resolution and high-resolution (CI) MS spectral investigations were conducted at
the University of Texas at Austin by Dr. M. Moini. The low-resolution MS studies were run on a
Finnegan MAT-TSQ-70 instrument and the high-resolution MS studies were conducted on a Micromass
ZAB-E spectrometer tuned to a resolution of 10,000 (10% valley definition). HPLC analyses were
conducted with the following Waters Associate Units: instrument A: 510 A pump, 510 B pump, Model
680 gradient controller, Model 490 multiwavelength detector, U6K injector; instrument B: 515 A pump,
515 B pump, Millennium chromatography manager, Waters 996 photodiode array detector, Rheodyne
7725i manual injector. In both cases the column was fitted with a µBondapak guardpak pre-column. The
product analyses were conducted with a C18 µBondapak (stainless steel) column (3.9 x 300 mm) using the
following linear gradient condition: 90% A (aqueous 0.025 M triethylammonium acetate, pH 6.5), 10% B
(acetonitrile) isocratic for 5 min, then from 90% A, 10% B to 45% A, 55% B in 30 min. The flow rate was
1 mL/min, and the eluent was monitored at 313 and 365 nm on instrument A, and from 200 to 400 nm on
instrument B. The HPLC solvents were filtered (aqueous solution with Millipore HVLP, 0.45 mm;

acetonitrile with Millipore HV, 0.45 mm) and degassed before utilization. Thin layer chromatography was
run on general purpose silica gel plates (20 x 20 cm; Aldrich No. Z12272-6). Tetrahydrofuran was
distilled from Na metal and benzophenone. The Ar used was O2-free (O2 < 5 ppm).
General Method for the Synthesis of C(7)-Aminosubstituted Porfiromycins. To an anhydrous
methanolic solution of 15 (1 equiv) was added a methanolic solution of the amine (0.5-10 equiv). The
reaction solution was stirred at rt (1-2 d) and the solvent was removed in vacuo and where appropriate
purified by PTLC (10% MeOH:CHCl3).
By using this procedure following compounds were prepared.
Compound (16). Using 15 (5.0 mg, 14 µmol), 20 (1.6 mg, 15 µmol) and MeOH (1.3 mL) gave (5.9 mg,
100%) 16 (2 d) as a red solid: HPLC tR: 24.6 min (instrument B); Rf 0.50 (10% MeOH-CHCl3); UV-vis
(MeOH) λmax 223, 365 nm; 1H NMR (pyridine-d5, 300 MHz) δ 1.10-1.14 (m, 1 H), 1.27-1.43 (m, 3 H),
1.52 (br dd, J = 12.0, 12.0 Hz, 1 H), 1.63 (br d, J = 12.0 Hz, 1 H), 1.95 (br d, J = 11.7 Hz, 1 H), 1.97 (s, 3
H), 2.12 (dd, J = 1.5, 4.5 Hz, 1 H), 2.25 (br d, J = 12.0 Hz, 1 H), 2.31 (s, 3 H), 2.61 (d, J = 4.5 Hz, 1 H),
2.90 (ddd, J = 3.6, 11.1, 11.7 Hz, 1 H), 3.05 (ddd, J = 3.6, 11.7, 12.0 Hz, 1 H), 3.28 (s, 3 H), 3.60 (dd, J =
1.5, 12.3 Hz, 1 H), 4.06 (dd, J = 4.5, 11.1 Hz, 1 H), 4.45 (d, J = 12.3 Hz, 1 H), 5.07 (dd, J = 10.5, 11.1 Hz,
1 H), 5.84 (dd, J = 4.5, 10.5 Hz, 1 H), 6.71 (s, 1 H); 13C NMR (pyridine-d5, 75 MHz) 8.8, 24.9, 26.2, 31.8,
33.6, 43.8, 44.1, 48.0, 48.6, 49.7, 51.7, 55.0, 63.2, 63.9, 106.8, 107.0, 115.9, 142.5, 148.3, 153.5, 158.9,
179.7 ppm; MS (+CI, methane) m/z 428 [M+1]+; Mr (+CI, methane) 428.228 95 (M+1)+ (calcd for
C22H30N5O4, 428.229 78).
Compound (17). Using 15 (6.0 mg, 17 µmol), 21 (1.9 mg, 17 µmol) and MeOH (1.3 mL) gave (7.1 mg,
100%) 17 (1 d) as a red solid: HPLC tR: 23.5 min (instrument B); Rf 0.47 (10% MeOH-CHCl3); UV-vis
(MeOH) λmax 223, 368 nm; 1H NMR (pyridine-d5, 300 MHz) δ 1.14-1.24 (m, 2 H), 1.28-1.35 (m, 2 H),
1.52 (br d, J = 11.4 Hz, 1 H), 1.63 (br d, J = 9.0 Hz, 1 H), 1.96 (br d, J = 11.4 Hz, 1 H), 2.00 (s, 3 H), 2.14
(dd, J = 1.5, 4.5 Hz, 1 H), 2.31 (s, 3 H), 2.31-2.35 (m, 1 H), 2.61 (d, J = 4.5 Hz, 1 H), 2.78 (ddd, J = 3.6,
11.4, 12.0 Hz, 1 H), 3.15 (ddd, J = 3.6, 11.7, 12.0 Hz, 1 H), 3.28 (s, 3 H), 3.58 (dd, J = 1.5, 12.6 Hz, 1 H),
4.13 (dd, J = 4.2, 11.1 Hz, 1 H), 4.37 (d, J = 12.6 Hz, 1 H), 5.08 (dd, J = 10.5, 11.1 Hz, 1 H), 5.45 (dd, J =
4.2, 10.5 Hz, 1 H), 6.88 (s, 1 H); 13C NMR (pyridine-d5, 75 MHz) 8.9, 24.9, 26.1, 31.6, 33.3, 43.8, 44.3,
46.3, 48.6, 49.7, 51.8, 54.8, 63.2, 63.8, 106.6, 107.2, 116.7, 142.5, 148.6, 153.5, 158.9, 179.9 ppm; MS
(+CI, methane) m/z 428 [M+1]+; Mr (+CI, methane) 428.228 81 (M+1)+ (calcd for C22H30N5O4, 428.229
78).
Compounds (18)17 and (19).17 Using 15 (3.2 mg, 9.0 µmol), 22 (1 mg, 9.0 µmol) and MeOH (0.3 mL)
gave 18 and 19 as a mixture (3.8 mg, 100%): HPLC tR: 22.0 and 22.4 min (instrument B); Rf 0.43 and

0.46 (10% MeOH-CHCl3); UV-vis (MeOH) λmax 223, 367 nm; MS (+CI, methane) m/z 428 [M+1]+; Mr
(+CI, methane) 428.230 03 [M+1]+ (calcd for C22H30N5O4, 428.229 78).
7-N-(trans-2-Hydroxycyclohexyl)porfiromycins (23) and (24). Using 15 (9 mg, 25 µmol), 27 (8 mg, 51
µmol), TEA (7 µL, 51 µmol) and MeOH (2.5 mL) provided compounds (23) and (24) (1 d) as a solid.
Compound (23)17 (3.7 mg, 32%): HPLC tR: 23.7 min (instrument B); Rf 0.49 (10% MeOH-CHCl3); UV-
vis (MeOH) λmax 220, 369 nm; 1H NMR (CDCl3, 300 MHz) δ 1.22-1.39 (m, 4 H), 1.72-1.77 (m, 2 H),
1.94-1.98 (m, 1 H), 2.01 (s, 3 H), 2.02-2.07 (m, 1 H), 2.27 (s, 3 H), 2.28-2.34 (m, 2 H), 3.18 (s, 3 H), 3.45-
3.48 (m, 1 H), 3.47 (d, J = 12.9 Hz, 1 H), 3.57 (dd, J = 4.5, 10.8 Hz, 1 H), 3.71-3.79 (m, 1 H), 4.25 (d, J =
12.9 Hz, 1 H), 4.35 (dd, J = 10.5, 10.8 Hz, 1 H), 4.70 (dd, J = 4.5, 10.5 Hz, 1 H), 6.22 (d, J = 10.2 Hz, 1
H); 13C NMR (CDCl3, 75 MHz) 10.3, 24.2, 24.5, 33.6, 33.7, 42.7, 43.1, 43.4, 46.4, 49.9, 50.0, 59.9, 62.7,
74.7, 104.3, 106.1, 109.9, 147.3, 155.4, 156.6, 176.2, 179.0 ppm; MS (+CI, methane) m/z 447 [M+1]+; Mr
(+CI, methane) 447.225 03 (M+1)+ (calcd for C22H31N4O6, 447.224 36).
Compound (24)17 (3.2 mg, 28%): HPLC tR: 25.2 min (instrument B); Rf 0.40 (10% MeOH-CHCl3); UV-
vis (MeOH) λmax 220, 369 nm; 1H NMR (CDCl3, 300 MHz) δ 1.25-1.36 (m, 4 H), 1.72-1.78 (m, 2 H),
1.94-1.98 (m, 1 H), 2.02 (s, 3 H), 2.04-2.09 (m, 1 H), 2.27 (s, 3 H), 2.29 (d, J = 4.2 Hz, 1 H), 2.34 (d, J =
4.2 Hz, 1 H), 3.18 (s, 3 H), 3.44-3.48 (m, 1 H), 3.47 (d, J = 12.9 Hz, 1 H), 3.57 (dd, J = 4.5, 10.5 Hz, 1 H),
3.72-3.79 (m, 1 H), 4.25 (d, J = 12.9 Hz, 1 H), 4.34 (dd, J = 10.5, 10.5 Hz, 1 H), 4.69 (dd, J = 4.5, 10.5
Hz, 1 H), 6.20 (d, J = 10.2 Hz, 1 H); 13C NMR (CDCl3, 75 MHz) 10.4, 24.2, 24.5, 33.5, 33.6, 42.8, 43.0,
43.4, 46.2, 49.9, 50.0, 59.8, 62.7, 74.7, 104.3, 106.2, 110.0, 147.3, 155.5, 156.6, 176.3, 179.1 ppm; MS
(+CI, methane) m/z 447 [M+1]+; Mr (+CI, methane) 447.223 35 (M+1)+ (calcd for C22H31N4O6, 447.224
36).
7-N-(cis-2-Hydroxycyclohexyl)porfiromycins (25) and (26). Using 15 (8 mg, 22 µmol), 28 (14 mg, 92
µmol), TEA (14 µL, 103 µmol) and MeOH (2.5 mL) provided compounds (25) and (26) (1 d) as a solid.
Compound (25)17 (2.5 mg, 25%): HPLC tR: 25.1 min (instrument B); Rf 0.52 (10% MeOH-CHCl3); UV-
vis (MeOH) λmax 220, 369 nm; 1H NMR (CDCl3, 300 MHz) δ 1.22-1.39 (m, 1 H), 1.57-1.61 (m, 2 H),
1.65-1.72 (m, 4 H), 1.86-1.89 (m, 1 H), 1.96 (s, 3 H), 2.27 (s, 3 H), 2.28-2.31 (m, 2 H), 3.18 (s, 3 H), 3.47
(dd, J = 1.8, 12.9 Hz, 1 H), 3.57 (dd, J = 4.2, 10.8 Hz, 1 H), 3.94-4.02 (m, 2 H), 4.25 (d, J = 12.9 Hz, 1
H), 4.35 (dd, J = 10.5, 10.8 Hz, 1 H), 4.72 (dd, J = 4.2, 10.5 Hz, 1 H), 6.82 (d, J = 9.3 Hz, 1 H), the NMR
sample contained triethylammonium hydrochloride: δ 1.25 (t, J = 7.2 Hz, 3 H) 3.72 (q, J = 7.2 Hz, 2 H);
13C NMR (CDCl3, 75 MHz) 10.0, 19.7, 23.7, 28.9, 32.1, 42.8, 43.0, 43.4, 46.4, 49.9, 50.0, 55.1, 62.7,
69.3, 104.0, 106.1, 110.0, 146.7, 155.3, 156.5, 176.4, 178.9 ppm; MS (+CI, methane) m/z 447 [M+1]+; Mr
(+CI, methane) 447.224 20 (M+1)+ (calcd for C22H31N4O6, 447.224 36).

Compound (26)17 (3.2 mg, 33%): HPLC tR: 25.8 min (instrument B); Rf 0.47 (10% MeOH-CHCl3); UV-
vis (MeOH) λmax 220, 369 nm; 1H NMR (CDCl3, 300 MHz) δ 1.24-1.38 (m, 1 H), 1.57-1.60 (m, 2 H),
1.66-1.71 (m, 4 H), 1.86-1.88 (m, 1 H), 1.97 (s, 3 H), 2.27 (s, 3 H), 2.29-2.33 (m, 2 H), 3.18 (s, 3 H), 3.47
(d, J = 13.2 Hz, 1 H), 3.57 (dd, J = 4.5, 10.8 Hz, 1 H), 3.92-3.98 (m, 2 H), 4.25 (d, J = 13.2 Hz, 1 H), 4.34
(dd, J = 10.5, 10.8 Hz, 1 H), 4.70 (dd, J = 4.5, 10.5 Hz, 1 H), 6.82 (d, J = 9.6 Hz, 1 H), the NMR sample
contained triethylammonium hydrochloride: δ 1.25 (t, J = 6.9 Hz, 3 H), 3.73 (q, J = 6.9 Hz, 2 H); 13C
NMR (CDCl3, 75 MHz) 10.0, 19.7, 23.8, 28.8, 32.2, 42.8, 43.0, 43.4, 46.4, 49.9, 50.0, 55.1, 62.7, 69.2,
104.0, 106.1, 110.0, 146.8, 155.4, 156.6, 176.4, 178.9 ppm; MS (+CI, methane) m/z 447 [M+1]+; Mr (+CI,
methane) 447.224 98 (M+1)+ (calcd for C22H31N4O6, 447.224 36).
Synthesis of 31 and 32. To the methanolic solution (0.4 mL) of 15 (3.8 mg, 10 µmol) and 30 (2.7 µL, 5
µmol) were added TEA (1.5 µL, 10 µmol) and catalytic amount of K2CO3 (2 d). The reaction mixture
provided 31 and 32 as solids.
Compound (31) (1 mg, 16%): HPLC tR: 31.3-33.0 min (instrument B); Rf 0.21 (10% MeOH-CHCl3); MS
(+CI, methane) m/z 592 [M+1]+; Mr (+CI, methane) 592.262 27 [M+1]+ (calcd for C28H42N5O5S2, 592.262
74).
Compound (32) (1.5 mg, 31%): HPLC tR: 36.7 min (instrument B); Rf 0.43 (10% MeOH-CHCl3); MS
(+CI, methane) m/z 922 [M+1]+; Mr (+CI, methane) 922.372 97 [M+1]+ (calcd for C44H58N8O10S2,
922.371 73).
Synthesis of C(7) Cyclized Porfiromycins (39) and (40). Using 15 (4.2 mg, 12 µmol), 38 (13 mg, 120
µmol) and MeOH (0.2 mL) gave 39 and 40 (2 d).
Compound (39)17 (1.6 mg, 31%): HPLC tR: 32.8 min (instrument A); Rf 0.63 (10% MeOH-CHCl3); UV-
vis (MeOH) λmax 236, 353 nm; 1H NMR (pyridine-d5, 300 MHz) δ 0.90-0.93 (m, 1 H), 1.23-1.35 (m, 3 H),
1.29 (d, J = 6.6 Hz, 3 H), 1.42-1.51 (m, 1 H), 1.58-1.63 (m, 1 H), 2.09 (dd, J = 1.8, 4.5 Hz, 1 H), 2.20 (s, 3
H), 2.50 (d, J = 4.5 Hz, 1 H), 2.69-2.72 (m, 1 H), 2.95-3.01 (m, 1 H), 3.03 (s, 3 H), 3.26 (q, J = 6.6 Hz, 1
H), 3.27-3.31 (m, 1 H), 3.38 (dd, J = 1.8, 12.6 Hz, 1 H), 3.62-3.68 (m, 1 H), 3.91 (dd, J = 4.5, 11.1 Hz, 1
H), 3.85 (d, J = 12.6 Hz, 1 H), 3.99 (dd, J = 6.3, 6.3 Hz, 1 H), 4.81 (dd, J = 10.5, 11.1 Hz, 1 H), 5.39 (dd,
J = 4.5, 10.5 Hz, 1 H); 13C NMR (pyridine-d5, 150 MHz) 7.8, 23.8, 25.9, 28.7, 42.7 (2C), 44.1, 45.3,
47.0, 49.5, 49.7, 51.4, 58.4, 62.3, 73.2, 97.3, 106.4, 121.6, 156.6, 158.0, 191.7, 193.4 ppm; MS (+CI,
methane) m/z 447 [M+1]+; Mr (+CI, methane) 447.224 02 (M+1)+ (calcd for C22H31N4O6 447.224 36).
Compound (40) (0.6 mg, 12%): HPLC tR: 30.6 min (instrument A); Rf 0.56 (10% MeOH-CHCl3); UV-vis
(MeOH) λmax 239, 365 nm; 1H NMR (pyridine-d5, 300 MHz) δ 0.95-0.98 (m, 1 H), 1.22-1.25 (m, 3 H),
1.32 (d, J = 6.6 Hz, 3 H), 1.46-1.50 (m, 1 H), 1.54-1.57 (m, 1 H), 2.04-2.08 (m, 1 H), 2.12 (br d, J = 4.5
Hz, 1 H), 2.20 (s, 3 H), 2.49-2.51 (m, 1 H), 2.54 (d, J = 4.5 Hz, 1 H), 3.12-3.16 (m, 1 H), 3.15 (s, 3 H),

3.41 (q, J = 6.6 Hz, 1 H), 3.44 (dd, J = 1.5, 12.3 Hz, 1 H), 3.46-3.49 (m, 1 H), 4.01 (dd, J = 4.5, 11.1 Hz, 1
H), 3.90 (d, J = 12.3 Hz, 1 H), 4.32 (dd, J = 6.0, 6.6 Hz, 1 H), 4.74 (dd, J = 10.5, 11.1 Hz, 1 H), 5.44 (dd,
J = 4.5, 10.5 Hz, 1 H); 13C NMR (pyridine-d5, 150 MHz) 7.4, 23.4, 25.7, 28.1, 42.8, 42.9, 44.4, 46.9,
47.0, 49.5, 49.7, 52.5, 58.2, 62.2, 72.9, 98.3, 106.3, 121.9, 157.0, 158.0, 193.0 ppm, the remaining signal
was not observed; MS (+CI, methane) m/z 447 [M+1]+; Mr (+CI, methane) 447.223 49 (M+1)+ (calcd for
C22H31N4O6 447.224 36).
7-N-(2-(S)-Hydroxypyrrolidine)porfiromycin (44). Using 15 (5.6 mg, 16 µmol), 42 (4.6 µL, 48 µmol)
and MeOH (0.5 mL) provided 44 as a green solid (5.2 mg, 78%) (2 h): HPLC tR: 24.1 min (instrument A);
Rf 0.40 (10% MeOH-CHCl3); UV-vis (MeOH) λmax 230, 379 nm; 1H NMR (pyridine-d5, 300 MHz) δ
1.50–1.54 (m, 1 H), 1.70-1.78 (m, 1 H), 1.84–1.89 (m, 1 H), 1.92 (s, 3 H), 2.02–2.08 (m, 1 H), 2.10 (d, J =
4.5 Hz, 1 H), 2.20 (s, 3 H), 2.50 (d, J = 4.5 Hz, 1 H), 3.10 (dd, J = 7.5, 11.4 Hz, 1 H), 3.13 (s, 3 H), 3.46
(d, J = 12.6 Hz, 1 H), 3.70-3.80 (m, 3 H), 3.92 (dd, J = 4.5, 11.1 Hz, 1 H), 4.46 (d, J = 12.6 Hz, 1 H), 4.77
1
(dd, J = 10.5, 11.1 Hz, 1 H), 5.18-5.25 (m, 1 H), 5.32 (dd, J = 4.5, 10.5 Hz, 1 H); H NMR (CD3OD, 600
MHz, 0 ºC) δ 1.71–1.75 (m, 1 H), 1.80-1.85 (m, 1 H), 1.86 (s, 3 H), 1.98-2.01 (m, 1 H), 2.10–2.15 (m, 1
H), 2.26 (s, 3 H), 2.44 (br s, 1 H), 2.51 (d, J = 4.6 Hz, 1 H), 3.19 (s, 3 H), 3.28-3.31 (m, 1 H), 3.41 (d, J =
12.9 Hz, 1 H), 3.42-3.49 (m, 2 H), 3.53 (dd, J = 4.3, 11.4 Hz, 1 H), 3.85-3.89 (m, 1 H), 4.15 (dd, J = 10.5,
11.4 Hz, 1 H), 4.20 (d, J = 12.9 Hz, 1 H), 4.64 (dd, J = 4.3, 10.5 Hz, 1 H), 4.91 (br s, 1 H); 13C NMR
(CD3OD, 150 MHz, 0 ºC) 13.6, 26.7, 29.4, 43.2, 44.2, 45.0, 47.8, 50.0, 50.6, 57.4, 63.4, 63.5, 65.4, 107.1,
112.7, 114.7, 153.2, 153.8, 159.8, 181.1, 182.1 ppm; MS (+CI, methane) m/z 433 [M+1]+; Mr (+CI,
methane) 433.207 76 (M+1)+ (calcd for C21H29N4O6, 433.208 71).
7-N-(2-(R)-Hydroxypyrrolidine)porfiromycin (45). Using 15 (3.2 mg, 9 µmol), 43 (2.6 µL, 27 µmol),
and MeOH (0.5 mL) provided 45 as a green solid (3.1 mg, 80%) (0.3 h): HPLC tR: 23.3 min (instrument
A); Rf 0.41 (10% MeOH-CHCl3); UV-vis (MeOH) λmax 233, 371 nm; 1H NMR (pyridine-d5, 300 MHz) δ
1.57–1.62 (m, 1 H), 1.74-1.80 (m, 1 H), 1.95–1.98 (m, 1 H), 2.03 (s, 3 H), 2.08–2.12 (m, 1 H), 2.13 (d, J =
4.5 Hz, 1 H), 2.21 (s, 3 H), 2.55 (d, J = 4.5 Hz, 1 H), 3.12 (dd, J = 8.1, 10.5 Hz, 1 H), 3.17 (s, 3 H), 3.52
(d, J = 12.6 Hz, 1 H), 3.77-3.86 (m, 3 H), 3.95 (dd, J = 4.4, 11.1 Hz, 1 H), 4.31 (d, J = 12.6 Hz, 1 H), 4.78
1
(dd, J = 10.5, 11.1 Hz, 1 H), 5.33-5.37 (m, 1 H), 5.53 (dd, J = 4.4, 10.5 Hz, 1 H); H NMR (CD3OD, 600
MHz, 0 ºC) δ 1.71–1.75 (m, 1 H), 1.81-1.83 (m, 1 H), 1.86 (s, 3 H), 1.98-2.00 (m, 1 H), 2.10–2.14 (m, 1
H), 2.25 (s, 3 H), 2.44 (br s, 1 H), 2.51 (d, J = 4.5 Hz, 1 H), 3.18 (s, 3 H), 3.33-3.36 (m, 1 H), 3.43 (dd, J =
0.9, 13.0 Hz, 1 H), 3.46-3.48 (m, 2 H), 3.53 (dd, J = 4.2, 11.4 Hz, 1 H), 3.85-3.89 (m, 1 H), 3.98 (d, J =
13.0 Hz, 1 H), 4.12 (dd, J = 10.6, 11.4 Hz, 1 H), 4.69 (dd, J = 4.2, 10.6 Hz, 1 H), 4.87 (br s, 1 H); 13C
NMR (CD3OD, 150 MHz, 0 ºC) 13.1, 26.6, 29.2, 43.1, 43.9, 45.1, 48.1, 49.9, 50.8, 57.4, 63.1, 63.6, 65.1,

107.2, 112.9, 114.5, 153.8, 154.9, 159.6, 180.2, 182.2 ppm; MS (+CI, methane) m/z 433 [M+1]+; Mr (+CI,
methane) 433.209 17 (M+1)+ (calcd for C21H29N4O6, 433.208 71).
Synthesis of 2-Acetylthiomethyl-1-[tert-butoxycarbonyl]piperidine (48). To a dry THF solution (3 mL)
of triphenylphosphine (144 mg, 0.55 mmol) was added diethyl azodicarboxylate (DEAD) (86 µL, 0.55
mmol) at rt under Ar. The reaction solution was cooled in an ice bath and additional THF (1.5 mL) was
added under Ar. After 20 min, a THF solution (1 mL) of 4723 (100 mg, 0.47 mmol) was added and then
thiolacetic acid (39 µL, 0.55 mmol) was added slowly with stirring at 0 ºC. The reaction solution was
allowed to stir at 0 ºC (1 h) and then at rt (16 h). The solvent was removed under low pressure and the
residue was purified using PTLC (2% MeOH-CHCl3) to give 48 as an oil (90 mg, 71%): Rf 0.72 (2%
MeOH-CHCl3); 1H NMR (CDCl3, 300 MHz) δ 1.38-1.41 (m, 1 H), 1.42 (s, 3 H), 1.57-1.64 (m, 5 H), 2.30
(s, 3 H), 2.73 (dd, J = 12.3, 13.2 Hz, 1 H), 3.04 (dd, J = 7.2, 13.5 Hz, 1 H), 3.14 (dd, J = 8.4, 13.5 Hz, 1
H), 3.96 (d, J = 13.2 Hz, 1 H), 4.25-4.30 (m, 1 H); 13C NMR (CDCl3, 75 MHz) 18.8, 25.2, 27.4, 28.4,
29.7, 30.5, 38.8, 49.5, 79.5, 154.9, 195.3 ppm; MS (+CI, methane) m/z 274 [M+1]+; Mr (+CI, methane)
274. 147 72 (M+1)+ (calcd for C13H24NO3S 274.147 69).
Synthesis of 2-Mercaptomethyl-1-[tert-butoxycarbonyl]piperidine (49). To a MeOH/H2O solution
(2:1, 3 mL) of 48 (23 mg, 0.08 mmol) was added K2CO3 (23 mg, 0.17 mmol) and the reaction mixture
was stirred at rt (25 min). The MeOH was removed under reduced pressure and residue was extracted with
CH2Cl2 (15 mL). The organic layer was dried (Na2SO4) and solvent was removed in vacuo to give crude
49 as an oil (20 mg, 93%): 1H NMR (CDCl3, 300 MHz) δ 1.30-1.38 (m, 2 H), 1.45 (s, 9 H), 1.52-1.62 (m,
3 H), 1.86 (d, J = 13.5 Hz, 1 H), 2.59 (dd, J = 8.4, 13.5 Hz, 1 H), 2.63-2.66 (m, 1 H), 2.78 (dd, J = 7.5,
13.5 Hz, 1 H), 3.98 (d, J = 12.9 Hz, 1 H), 4.18-4.22 (m, 1 H); 13C NMR (CDCl3, 75 MHz) 18.7, 24.5,
25.2, 26.3, 28.4, 39.1, 52.9, 79.5, 155.1 ppm; MS (+CI, methane) m/z 232 [M+1]+; Mr (+CI, methane)
232.135 85 (M+1)+ (calcd for C11H22NO2S 232.137 13).
Synthesis of 2-(Mercaptomethyl)piperidine·HI (46). To a CDCl3 solution (1 mL) of 49 (8 mg, 35 µmol)
was added trimethylsilyl iodide (6.1 µL, 55 µmol) under Ar. The reaction solution was stirred at rt (20
min) and then MeOH (1 mL) was added, and the reaction solution was stirred for additional 17 h. The
solvent was removed in vacuo to give crude 46 as an oil (9 mg, 100%): 1H NMR (D2O, 300 MHz) δ 1.47-
1.65 (m, 3 H), 1.87-1.90 (m, 2 H), 2.00 (d, J = 13.5 Hz, 1 H), 2.68 (dd, J = 7.2, 15.0 Hz, 1 H), 2.90 (dd, J
= 5.1, 15.0 Hz, 1 H), 2.96-3.05 (m, 1 H), 3.20-3.22 (m, 1 H), 3.44 (d, J = 13.2 Hz, 1 H); 13C NMR (D2O,
75 MHz) 21.4, 21.8, 26.6, 27.5, 45.0, 58.5 ppm; MS (+CI, methane) m/z 132 [(M-HI)+1]+.
Reaction of 15 with 2-(Mercaptomethyl)piperidine·HI (46). To a dry methanolic solution (0.6 mL) of
15 (4.5 mg, 12 µmol) and 46 (6.4 mg, 24 µmol) were added TEA (3.4 µL, 24 µmol) and a catalytic
amount of K2CO3 under Ar. The reaction mixture was stirred at rt under Ar. After 15 min the color of

reaction mixture changed from purple to orange and an orange color solid precipitated from solution. The
solvent was removed in vacuo under low pressure and the residue was purified by PTLC (10% MeOH-
CHCl3) to give 50 (1.5 mg, 37%) as an orange solid (HPLC tR 22.5 min, Rf 0.42 (10% MeOH-CHCl3)).
The separated solid was coinjected with authentic 5024 and showed a single peak at 22.5 min.
ACKNOWLEDGEMENTS
We thank Drs. M. Kasai and H. Arai, Kyowa Hakko Kogyo Pharmaceutical Research Laboratories,
Osaka, Japan for the generous supply of 15. This investigation was supported by NIH grant CA29756.
REFERENCES
1.
S.K. Carter and S.T. Crooke, ‘Mitomycin C: Current Status and New Developments’, Academic
Press, New York, 1979.
2.
V.N. Iyer and W. Szybalski, Science, 1964, 145, 55; W.A. Remers, ‘The Chemistry Of Antitumor
Antibiotics,’ Wiley, New York, 1979; R.W. Frank and M. Tomasz, ‘The Chemistry of Antitumor
Agents,’ ed. by D.E.V. Wilman, Blackie and Sons, Ltd., Scotland, 1990; pp. 379-394; J.R. Fisher,
and P.A. Aristoff, Prog. Drug Res., 1988, 32, 411; H.W. Moore and R. Czerniak, Med. Res. Rev.,
1981, 1, 249; M. Tomasz and Y. Palom, Pharmacol. Ther., 1997, 76, 73.
3.
4.
W.T. Bradner, W.A. Remers, and D.M. Vyas, Anticancer Res., 1989, 9, 1095.
M. Kono, Y. Saitoh, M. Kasai, A. Sato, K. Shirahata, M. Morimoto, and T. Ashizawa, Chem.
Pharm. Bull., 1989, 37, 1128.
5.
Compound (2) (KW-2149): T. Ashizawa, M. Okabe, K. Gomi, and T. Hirata, Anti-Cancer Drugs,
1993, 4, 181; Y. Ohe, K. Nakagawa, Y. Fujiwara, Y. Sasaki, K. Minato, M. Bungo, S. Niimi, N.
Horichi, M. Fukuda, and N. Saijo, Cancer Res., 1989, 49, 4098; M. Morimoto, T. Ashizawa, H.
Ohno, M. Azuma, E. Kobayashi, M. Okabe, K. Gomi, M. Kono, Y. Saitoh, Y. Kanda, H. Arai, A.
Sato, M. Kasai, and T. Tsuruo, Cancer Res., 1991, 51, 110; T. Tsuruo, Y. Sudo, N. Asami, M.
Inaba, and M. Morimoto, Cancer Chemother. Pharmacol., 1990, 27, 89; L. Dirix, E.E.O.
Gheuens, S. van der Heyden, A.T. van Oosterom, and E.A. De Bruijn, Anti-Cancer Drugs, 1994,
5, 343; J.R.W. Masters, R.J. Know, J.A. Hartley, L.R. Kelland, H.R. Hendriks, and T. Connors,
Biochem. Pharmacol., 1997, 53, 279; T. Ashizawa, A. Okamoto, M. Okabe, S. Kobayashi, H.
Arai, H. Saito, M. Kasai, and K. Gomi, Anti-Cancer Drugs, 1995, 6, 763; T. Yasuzawa and K.B.
Tomer, Bioconj. Chem., 1997, 8, 391; E. Kobayashi, M. Okabe, M. Kono, H. Arai, M. Kasai, K.
Gomi, J.-H. Lee, M. Inaba, and T. Tsuruo, Cancer Chemother. Pharmacol., 1993, 32, 20; S.
Kobayshi, J. Ushiki, K. Takai, S. Okumura, M. Kono, M. Kasai, K. Gomi, M. Morimoto, H.
Ueno, and T. Hirata, Cancer Chemother. Pharmacol., 1993, 32, 143; S.R. McAdam, R.J. Knox,
J.A. Hartley, and J. R.W. Masters, Biochem. Pharmacol., 1998, 55, 1777.

6.
7.
D.M. Vyas, Y. Chiang, D. Benigni, W.C. Rose, and W.T. Bradner, ‘Recent Advances in
Chemotherapy. Anticancer Section,’ ed. by J. Tshigami, University of Tokyo Press, Tokyo, 1985,
pp. 485-486.
Compound (3) (BMS-181174): W.T. Bradner, W.C. Rose, J.E. Schurig, and A.P. Florczyk, Invest.
New Drugs, 1990, 8, S1; L. Dusre, S. Rajagopalan, H.M. Eliot, J.M. Covey, and B.K. Sinha,
Cancer Res., 1990, 50, 648; B.H. Xu and S.V. Singh, Cancer Res., 1992, 52, 6666; S. Rockwell,
B. Kemple, and M. Kelley, Biochem. Pharmacol., 1995, 50, 1239; B.H. Xu, V. Gupta, and S.V.
Singh, Br. J. Cancer, 1994, 69, 242.
8.
L. Dirix, G. Catimel, I. Koier, A. Prove, D. Schrijvers, E. Joossens, E. de Bruijn, C. Ardiet, E.
Evene, A. Dumortier, M. Clavel, and A. van Oosterom, Anti-Cancer Drugs, 1995, 6, 53; T.W.
Doyle and D.M. Vyas, Cancer Treat. Rev., 1990, 17, 127.
9.
Q.-Y. He, H. Maruenda, and M. Tomasz, J. Am. Chem. Soc., 1994, 116, 9349.
H. Kohn and S. Wang, Tetrahedron Lett., 1996, 37, 2337.
10.
11.
12.
13.
S. Wang and H. Kohn, J. Med. Chem., 1999, 42, 788.
M. Kono, Y. Saitoh, K. Shirahata, Y. Arai, and S. Ishii, J. Am. Chem. Soc., 1987, 109, 7224.
M. Kono, Y. Saitoh, M. Kasai, K. Shirahata, M. Morimoto, and T. Ashizawa, J. Antibiot., 1993,
46, 1428.
14.
15.
16.
I. Usubuchi, Y. Sobajima, T. Hongo, T. Kawaguchi, M. Sugawara, M. Matsui, S. Wakaki, and K.
Uzu, Gann, 1967, 58, 307.
B.S. Iyengar, S.M. Sami, S.E. Tarnow, W.A. Remers, W.T. Bradner, and J.E. Schurig, J. Med.
Chem., 1983, 26, 1453.
Y. Saito, M. Kasai, K. Shirahata, M. Kono, M. Morimoto, and T. Ashizawa (Kyowa Hakko
Kogyo C., Ltd.), U.S. Patent 4,853,385, (Aug. 1, 1989), Eur. Pat. Appl. EP 287,855, Oct. 26,
1988, JP Appl. 63246379, (March 31, 1987) (Chem. Abstr. 1989, 111, 7145v).
We were not able to stereochemically assign the structures for this pair of diasteromers.
S. Wang and H. Kohn, J. Org. Chem., 1997, 62, 5404.
17.
18.
19.
20.
21.
22.
23.
24.
W.S. Johnson and E.N. Schubert, J. Am. Chem. Soc., 1950, 72, 2187.
D. Choi, B. Yoo, K.L. Colson, G.E. Martin, and H. Kohn, J. Org. Chem., 1995, 60, 3391.
T. Taguchi and M. Kojima, J. Am. Chem. Soc., 1956, 78, 1464.
Y. Kanda and M. Kasai, J. Org. Chem., 1990, 55, 2515.
F. Sánchez-Sancho and B. Herradón, Tetrahedron: Asymm., 1998, 9, 1951.
S.J. Danishefsky and M. Egbertson, J. Am. Chem. Soc., 1986, 108, 4648; V.-S. Li, D. Choi, M.-s.
Tang, and H. Kohn, J. Am Chem. Soc., 1996, 118, 3765.

25.
Y. Na, Ph.D. Thesis, University of Houston, 2000.