Full text of DOI:10.1016/S0040-4020(01)83202-6

Tetrahedron. Vol. 29,pp. 1801 to 1806. Pergamon Press 1973. Printed in Great Britain
S Y N T H E S I S OF C Y T O S I N I N E , THE N U C L E O S I D E
C O M P O N E N T OF ANTIBIOTIC BLASTICIDIN S*
T. KONDO, H. NAKAI and T. GOTO~"
Department of Agricultural Chemistry,NagoyaUniversity,Chikusa, Nagoya 464, Japan
(ReceivedinJapan 9January 1973;Received in the UKfor publication 13 February 1973)
Abstract--The firsttotal synthesis ofcytosinine(2) is described.
Blasticidin S (1)1 is a nucleoside antibiotic pro-
duced by Streptomyces griseochromogenes and
double bond to the 2',3'-position. This method has
been applied to the synthesis ofpurine nucleosides,11
has been used extensively as an excellent fungicide but pyrimidines do not condense with giycals in the
usual manner. We found12 that triacetylglucal could
be condensed with silylated uracil in the presence
of SbCI5 to afford a mixture of a- and ~anomers of
the 2',3'-unsaturated nuclooside, which could be
separated easily by column chromatography. Al-
though this procedure has an intrinsic disadvantage
to produce the anomer mixture, we applied it for
the synthesis of cytosinine since the reaction is
against the virulent fungus, Piricularia oryzae, a
serious cause of rice blast disease in Japan.2 It was
also reported that the antibiotic inhibits the growth
of tobacco mosaic virus3 and has antitumor activity
for certain carcinomas.4 The structure5'e and ab-
solute configuration7 have been elucidated chemi-
cally by Otake et al and confirmed by X-ray analy-
sis.8 Controlled acid hydrolysis of blasticidin S
yielded cytosinine (2), a peculiar nucleoside, and simple and the yield is fairly good.
blastidic acid (3), a new ~amino acid.~In this paper
we describe the first synthesis of cytosinine (2).
We have chosen triacetylgalactal (4) and silyl-
ated uracil 5, instead of 4-aminouronic acid and/or
cytosine, as the starting materials by taking the fol-
lowing preliminary experiments into consideration:
(a) 4-aminosugars could not be converted to the
corresponding glycals through their halo deriva-
tives, (b) an amino group could not be introduced
into the C-4' position of 2',3'-unsaturated uronic
nucleosides, and (c) silylated N-acetylcytosine
could be condensed with triacetylgalactal only in a
very low yield and the acyl protecting group in
cytosine is too unstable to carry out further modi-
fications.
Condensation of triacetylgalactal (4)with 4 eq of
silylated uracil 5 in the presence of 8 eq of SbCI5
afforded an anomeric mixture of 1-(4',6'-di-O-
acetyl-2' ,3'-dideoxy-v-threo-hex-2'-enopyranosyl)-
uracils from which crystalline a-anomer 7 and
amorphous ~anomer 6 could be isolated in yields
of 40 and 24%, respectively, by means of column
chromatography on silica gel. A trace amount of
3-uracilyl-3-deoxygiycal 8 was also obtained from
NH2
HOOC
O
CHa
NH2
H ~
)
I
$1
-
-
/C--NCH~CH2CHCH2~ , NH
8
H~N
Blastidic acid (3) (
Blasticidin S (1)
F~ 1.
, Cytosinine(2)
There seem to be two main procedures for intro-
duction of a 2',3'-double bond in pyranosyl nucleo-
sides. One involves the elimination of 2',Y-trans- the column; structure of the glycal being tentatively
assigned to be 4,6-di-O-acetyl-l,2,3-trideoxy-3-
(1 '-uracilyl)-v-xy/o-hex- 1-enopyranose by analysis
of NMR spectrum and from analogy of the previous
work.13 The fl-anomer of the 2'-enopyranosyluracil
6 was deacetylated with sodium methoxide to the
crystalline diol 9. Assignment of the structure ofthe
diol 9 was made unequivocally by derivation of it
by selective mesylation followed by acetylation to
the diol 4-acetate 6-mesylate 10, whose NMR spec-
trum was completely superimposable with that of
diaxially oriented substituents such as iodosuif-
onate or disulfonate with iodide and zinc) This
method has been applied to the synthetic approach
towards cytosinine by Watanabe et aLto The other
method involves direct condensation of a glycal
with a base with simultaneous migration of the
*Preliminary communication, Tetrahedron Letters,
1881 (1972).
?To whomcorrespondenceshouldbe addressed.
1801

1802
T. KONDO, H. NAKAI and T. GOTO
O
OTMS
CH20Ac
AeO~ = ~ =
CHs0Ac
CH~OAc
+
A c O ~ m ~
A ¢ O ~
TMSO 5
+
4
O
O
8
7
Fig2.
the compound derived from the nucleoside 1|t4 of tatively the 4-mesylate 15. It is an allylic mesylate
known configuration by the following transforma- and strongly susceptible toward nucleophilic dis-
tions: mesylation of 11 followed by selective dis-
placements and hence treatment of the mesylate
placement15 with sodium benzoate gave 13, which with a saturated lithium azide solution in DMF at
was debenzoylated and acetylated. 0° for 15 min easily afforded the azide 16 in 78%
Selective benzoylation of the diol 9 in pyridine yield. The signal of the anomeric proton in the azide
16 is split into quartet (J = 2.0 Hz) by two olefinic
with benzoyl chloride according to Reist et al1~ af-
forded the 6-monobenzoate 14 only in a low yield. protons and C-4' proton, suggesting that the double
The yield was improved to ca 50% by carrying out bond is in its original 2',Y-position. The coupling
constant between 3'-H and 4'-H of the starting
mesylate 15 is 5.0 Hz, whereas NMR of the azide
16 shows Jr.4, = 2.0 Hz, thus strongly suggesting
the reaction using 1% benzoyl chloride in CH2CIz
a t - 2 0° Mesylation of the 6-benzoate 14 with mesyl
chloride and pyridine at - 10° gave almost quanti-
O
O
O
R O H 2 C
[
I
)
A¢
17:
R
R
=
=
B z
H
6:
9:
R
R
=
R'
=
A c
H
'
16
18:
= R ' =
14:
15:
R
R
=
=
B z , R'
B z , R'
=
=
H
M s
NHR'
O
S
ROOC o ' N ~
ROOC 0 ~ '
R'NH
A c N H
19
C H a ~ N H
2: R = H , R ' = H
22:
23:
R
R
=
=
CH~
H
24: R = CH~, R' ---- Ac
Fig 3.

Synthesis of cytosinine
1803
that the SN 2 reaction occurred at the C-4' position
and an erythro sugar was produced. When the reac-
tion was carried out at a more elevated temp and/or
for a longer reaction time this displacement r e a c -
tion was accompanied partially by an allylic rear-
rangement17 to give a 3',4'-unsaturated 2'-azide.
Reduction of the azide group in 16 was accomp-
lished with CrCI~ according to Kirk and Wilson's
methodTM to give the corresponding amine, which
was isolated, after acetylation with acetic anhydride
and pyridine, as the acetamide 17 in a 60% yield.
Neutralization of the reduction mixture must be
carried out carefully with N a H C O 3 aq to prevent
O---> N benzoyl migration. Sodium borohydride
Conversion of the uracinine 19 into cytosinine
(2) was accomplished by the procedure ofWatanabe
et ai.2° Thus, the ester 19 was refluxed in pyridine
with P2Ss for 1 hr to give N-thioacetylthiouracinine
methyl ester 22, whose structure was suggested
from the UV absorption bands at 268 and 328 nm.
To prevent amide formation in the next amination
step, the methyl ester 22 was hydrolyzed with 1 N
NaOH in methanol at room temp to the carboxylic
acid 23, which was dissolved in methanol previous-
ly saturated with ammonia at - 5° and heated in an
autoclave at 100° for 24 hr. After evaporation of
solvent, the residue was absorbed on an Amberlite
IRA-410 (OH- form) column. Elution of the col-
could also be used for reduction of the azide 16 but umn with 0-SN HC1 afforded cytosimne (2) as
the yield was very low.TM Debenzoylation of the
amide 17 with methoxide in methanol gave the
crystalline amidoalcohol 18 in quantitative yield.
Oxidation of the amidoalcohol 18 to the corre-
crystalline hydrochloride, IR spectrum of which
(KBr disc) is superimposable to that of an authentic
specimen prepared from blasticidin S (1) according
to the method of Otake et al.6 Further character-
sponding amidocarboxylic acid was achieved suc- izations were made as follows: acetylation of cyto-
sinine (2) with acetic anhydride and pyridine fol-
anhydride to a solution of 18 in acetone-DMF at lowed by methylation with diazomethane in ether
cessfully by addition of a large excess of chromic
afforded N,N'-diacetylcytosinine methyl ester
(24). IR, UV, NMR and ORD spectra as well as
m.p. of the synthetic 24 were identical with those of
the authentic sample6 prepared from blasticidin S,1
thus confirming the structure including the absolute
configuration.
room temp and by allowing the resulting mixture
to stand for 30 min. The reaction mixture was sub-
sequently treated with excess diazomethane in
ether and, after evaporation of the volatile solvents,
the residue was chromatographed on a silica gel
column to remove chromium compounds giving the
amidocarboxylic acid methyl ester (N-acetylurac-
inine methyl ester;~ 19) in 42% yield. J4,,5-value in
the NMR spectrum of 19 is 9.0 Hz, thus confirm-
ing the erythro configuration at the C-4' and C-5'
positions.
Conversion of the azide 16 into the uracinine
derivative 19 by another route involving oxidation
of the prim alcohol to an uronic acid followed by
reduction of the azide group was also attempted.
Thus, debenzoylation of 16 with sodium methoxide
gave the azidoalcohol 20, which was oxidized by
the procedure described above to give the methyl
azidouronate 21 in a yield of 81%; the structure 21
being confirmed from N M R [8 3.91 ppm (3H, s)]
and IR (2200 cm -1) spectra. Reduction of 21 by
CrClz, however, afforded an intractable mixture,
from which the expected product 19 could not be
isolated.
EXPERIMENTAL
All m.ps are uncorrected. The following spectrometers
were used: IR: JASCO IR-G and IR-E; UV: Hitachi
EPS-3T; ORD: JASCO ORD/UV-5; NMR: JEOL
4H-100 and MH-100 (100 MHz). Chemical shifts (8) are
in ppm from int. TMS and coupling constants (J) in Hz
(accuracy -+0.3 Hz). J-values marked by an asterisk were
confirmed by double resonance experiments. TLC was
performed on silica gel PF 254 (Merck) using CH2CI2-
MeOH (30: 1) as the eluant, unless otherwise described.
Silica gel (100 mesh, Kanto Chemical Co.) was used for
column chromatography.
Condensation of triacetylgalactal (4) and 2,4-bis(tri-
methylsilyl)uracil (5). SbC15(12 ml) was added to a stirred
soln of 4 (4-58g) and 5 (14.5 g) in dry EtOAc (200 ml) at
room temp under an anhydrous condition. The temp of
the mixture rose to about 50° and then the mixture was
allowed to stand at room temp for 15 min. The soln was
6
R
o
M,OH. - I
RO
11: R = H
12: R = Ms
13:
I0:
R
R
=
=
B z
A c
20: R = CH2OH
21: R = COOCHs
Fig4.

T. KONDO, H. NAKAI and T. GOTO
1804
13. Compound 13 (16 mg) was dissolved in MeOH con-
talning 0"01M NaOMe (l-5ml). After 1 hr, the mixture
was neutralized with Amberlite IRC-50 (H+ form) and
evaporated to dryness. The residue was acetylated with
Acs~) and pyridine to afford 10; NMR (CDCI3) 6.54
(H-I'), 5.95 (2'), 6.46 (Y), 5.21 (4'), 4.31 (5' and 6').
5.80 (5), 7.27 (6), 9.1 (NH), 3.05 (CHaSO2), 2.13 (Ac).
(b) From the diol 9. Mesyl chloride (10/d) was added in
one portion to a stirred soln of 9 (15 m8) in pyridine (0-4
ml) at - 20° and then the soln was kept at 0° until the start-
ing material was almost disappeared (monitored by TLC).
Evaporation followed by acetylation with Ac~O and pyri-
dine afforded the crude 10, which was purified by TLC.
NMR spectrum of 10 obtained from 9 is completely super-
imposable to that of 10 obtained from 13.
l - ( 6 ' - O - B e n z o y l - 2 ' ,3'-dideoxy-fl-D-threo-hex-2'-enopyr-
anosyl)uracil (14). To a well stirred soln of 9 (1.57g) in
anhyd pyridine (60 ml) was added dropwise a soln of ben-
zoyl chloride in CH2CI~ (1%, 250 ml) at - 4 0° and then
temp of the mixture was kept at - 20°. When the starting
material had almost disappeared (monitored by TLC), the
mixture was treated with dry MeOH (50 ml) at - 10° and
then evaporated in v a c u o below 5°. The residue was
chromatographed on a silica gel column by use ofCH2CI2--
MeOH (30:1) as the eluant, and then crystallized from
isopropanol to give 14 (1"058; 49%), m.p. 175°. (Found:
C, 59.69; H, 4.64; N, 8.25. C17HlcN2Oe requires: C, 59.30;
H, 4.68; N, 8-14%); NMR (CDCIa) 6.49 (H-I'), 5.85 (2'),
6.49 (3'), 4.15 (4' and 5'), 4.70 and 4.50 (6'), 5.80 (5),
8"1 and 7"5 (arom), Jz,.s, = 10, Js.s = 8.
l - ( 6 ' - O - B e n z o y l - 4 ' - O - m e s y l - 2 ' , 3 ' - d i d e o x y - f l - D - t h r e o -
hex-2'-enopyranosyOuracil (15). To a soln of 14 (808 mg)
in a mixture of anhyd pyHdine (12 ml) and CH2CI~ (20 ml)
was added dropwise at - 40o mesyl chloride (6 ml). The
temp of the mixture was allowed to rise to - 10° and then
kept at this temp until the reaction was completed (moni-
tored by TLC). The soin was diluted with CHsCls (100
ml), washed successively with ice-cold water, cold 1 N
HCI and NaHCOs aq, and evaporated below 400. For re-
moral of excess mesyl chloride, the residue was chrom-
atographed on a short silica gel column using C H ~ I r -
MeOH (30:1) as the eluant. The eluted soln was evapor-
ated at a temp as low as possible to give 15 as an amor-
phous solid (925 rag, ca 100%), NMR (CDCla) 6.66
(H-I'), 6.07 (2'), 6.56(Y), 5-13 (4'), 4.6-4.3 (5' and@),
diluted with CHsCIz (450 mi), gradually poured into
NaHCOs aq with stirring, and then the stirring was con-
tinued for further 1-5 hr. After the ppt was filtered off, the
organic layer was separated, washed
4 times with
NaHCOs aq, dried over NazSO4 and evaporated to dry-
ness. The residue was chromatographed on a silica gel
column (250g) by using CH~K~I~-MeOH (30: 1) as the
eluant to afford two anomers of the 2-enopyranosyl nuc-
leosides and a trace amount of 8. One of the anomers,
l- (4' ,6'-di-O-acetyl-2'Y-dideoxy-fl-D-threo-hex-2-eno-
pyranosyl)uracil (6), was obtained as an amorphous solid
(1.29g; 24%); UV (MeOH) 258 nm (e 9800); (MeOH-
NaOH) 258 (7500); NMR (CDCIa) 6.55 (H-I'), 5.92 (2'),
6.43 (3'), 5.17 (4'), 4.20 (5' and 6'), 5.85 (5), 7-35 (6),
9.47 (NH), 2.16 (At), J1,.2, = 1.5", J~,.3, = 10.0, J8,.4, =
6 . 0 " , J4,.5, ffi
~ 0, Jz,.3, = 1"5", J l ' . 4 ' = 1-5". The other
anomer, 1-(4',6'-di-O-acetyl-2',Y-dideoxy-a-D-threo-hex-
2-enopyranosyl)uracil (7), was crystallized from EtOH
as needles (2.166; 40%), m.p. 148-149°. (Found: C, 51.46;
H, 5.01; N, 8.51. CI~I~eN207 requires: C, 51.85; H, 4-97;
N, 8.64%); UV (MeOH) 260nm (e 10500); (MeOH-
NaOH) 260 (7900); NMR (CDCI3) 6.45 (H-I'), 6.04 (2'),
6-55 (3'), 5.23 (4'), 4.4-3.9 (5' and 6'), 5.71 (5), 7.32 (6),
9.61 (NH), 2.10 (Ac), 2.05 (Ac), Jr.2, = 3.0", ./2,.3, = 10,
-/3'.¢ = 5*, J v . s ' = 2", Js,e = 8. 4,6-Di-O-acetyl-l,2,3-
trideoxy-3-(1 '-uracilyl)- D-xy/o(?)-hex- l-enopyranose (8):
NMR (CDCIa) 6.85 (H-l), 4.72 (2), 4.91 (4), 4-3--4.1 (5
and 6), 5-75 (5'), 7.52 (6'), 2.08 (Ac), 2.01 (Ac), JL2 ~ 6-5,
J~.3 = 5.0, Jl.s = 1"5, J~,.¢ = 8.
1-(2',3'-Dideoxy-fl-D-threo-hex-2'-enopyranosyl)uracil
(9). The diacetate 6 (2.566) was dissolved in MeOH
containing 0.2M NaOMe (75 ml) and the mixture was
allowed to stand at room temp for 3 hr. The soln was neut-
ralized with Amberlite IRC-50 (H+ form), filtered and
evaporated in v a c u o to give the diol 9, which was crystal-
lized from isopropanol as prisms (1.29g; 77%), m.p. 177-
178°. (Found: C, 50.19; H, 5.04; N, 11.77. C~0HnN~O~
requires: C, 50.00; H, 5.04; N, 11.66%); UV (MeOH)
259nm (e 11400).
1- (4',6'-Di-O-mesyl-2',3'-dideoxy-~-D-erythro-hex-2'-
enopyranosyl)uracil (12). Mesyl chloride ( 2 . 0im) was
added dropwise to a stirred soln of the diol 11~ (750 rng)
in anhyd pyridine (20 ml). During addition the temp was
kept below - 5° and then maintained at 0° for 48 hr. Water
(2 mi) was added to the soin at room temp to destroy ex-
cess mesyl chloride. After 2 hr the mixture was diluted 5.78 (5), 7-35 (6), 9.33 (NH), 7-95 and 7-45 (arom), 3-12
with CH~CI~ and water. The organic layer was washed
successively with water and 1 N HCI, dried and evap-
orated to dryness. The residue was separated by TLC to
(CHaSOs), J~'.s' = 10, Js',¢ ffi 5", Jl'.s' -'- 1", Js~ = 8.
1-( 6 '-O-Benzoyl-4'-azido-2',3',4'-trideoxy-~-D-erythro"
hex-2'-enopyranosyOuracil (16). The mesylate 15 (1.61 g)
give the dimesylate 12 as an amorphous solid (785 mg); was added a t - 5 ° in a soln of anhyd LiNa (126) in dry
DMF (120ml), and the mixture was allowed to stand at
0* for 15 rain. The soln was poured onto stirred ice-cold
water and extracted with CH2C12. The extract was re-
peatedly washed with ice-cold water to remove DMF,
dried over Na~SO4 and evaporated in v a c u o below 15°.
The residue was purified by preparative TLC to give the
azide 16 as an amorphous solid (1.106, 78%); N M R
(CDCIa) 6.58 (H-I'), 5-89 (2'), 6.35 (Y), 4-3-3.8 (4' and
5'), 4.60 and 4-58 (6'), 5.75 (5), 7.25 (6), 8.14 and 7.58
( a r o m ) , J1,,2, ffi 2"0, J~'.s' ffi 10, Ja'.¢ -~ 2"0*, J t , , 3 , ffi 2"0*,
J1'.¢ = 2"0", Js'.¢ = 2"5 and 5.0, Je'~lm~ = 14"0, Js~----8;
IR (CHCIa) 2200 cm-1.
NMR (CDaCOCDa) 6-71 (H-I'), 6-25 (2'), 6-57 (3'), 5"17
(4') 8"12 (NH), 4.6--4.3 (5' and 6'), 5.70 (5), 7.40 (6), 3.25
(CHaSO0, 3-12(CHa-SOJ.
l-( 4' - O - Be n z o y l - 6' - m e s y l - 2! , 3 '-dideoxy-fl-v-threo-hex-
2'-enopyranosyl)aracil (13). The dimesylate 12 (53 mg) and
sodium benzoate (26 mg) (freshly fused before use) was
dissolved under stirring in hexamethylphosphortriamide
(1.5 ml). After being kept at room temp for 12 hr, the mix-
ture was diluted with CH~:~I~, thoroughly washed with
water and evaporated. Separation by TLC afforded the
monobenzoate 12 as an amorphous sofid (30 rng); NMR
(CDCIa) 6.26 (H-I'), 5.99 (2'), 6-60 (3'), 5.44 (4'), 4.42
(5' and 6'), 7-30 (6), 5.77 (5), 8.05 and 7.5 (5H, arom),
1- (4 ' -A ce t a m i d o - 6' - O - b e n z o y l - 2 ' ,3 ' ,4 ' - trideoxy-fl- D-
erythro-hex-2'-enopyranosyl)uracil
(17).
A
chromous
3"03 (CHaSO,), Jx'~' =
~ O, J~'.s' = 10, Jx's' -- 1, J~,.¢ =
chloride soin (158 ml) prepared according to the method
of Rosenkranz et a F was gradually added to a stirred
soln of 16 (2.43 g) in a mixture of acetone and water (2: 1,
5, J¢.~,= ~ 0, J~,e = 8.
l - ( 4 ' - O - A c e t y l - 6 ' - O - m e s y l - 2 ' ,3'-dideoxy-fl-D-threo-hex-
2'-enopyranosyOuracil (10). (a) From the m o n o b e n z o a t e

Synthesis of cytosinine
1805
removed by passing through a short silica gel column, the
CHzCI2 soln was evaporated to dryness and the residue
was subjected to TLC separations to give 22 (226 mg,
46%) and N-acetylthiouracinine methyl ester (30rag);
UV (MeOH) 275 nm. The former compound (22) was
crystallized from EtOH as yellow needles, m.p. 204-
205°. (Found: C, 45.86; H, 4-68; N, 12-53. C18H15NsO4S~
requires: C, 45-75; H, 4.43; N, 12.31%); UV (MeOH)
268 nm (e 17000), 328 (21200); NMR (CDCI~CD3OD
1 : 1) 6-50 (H-I'), 5.82 (2'), 6.25 (3'), 5-68 (4'), 4.55 (5'),
6.40 (5), 7-23 (6), 3.71 (CH30), 2-48 (CH3CS), J1,.2, =
110 ml) under Nz at at room temp. During the addition
Nz gas evolved from the soln. After 10 rain, the mixture
was carefully neutralized with NaI-ICOa aq, filtered and
evaporated to dryness in vacuo. Repeated extractions
from the residue with CH~CIr-MeOH (1 : 1) gave an ex-
tract which, after being passed through a very short
column of silica gel, was evaporated to dryness to afford a
crude amine, which had no azide absorption band in its IR.
The amine was treated with Ac~3 and pyridine (1:2,
450 rrd) overnight, and the soln was evaporated to dry-
ness. The residue was purified by column chromatog-
raphy using silica gel to give the acetamide 17 as an
amorphous solid (1-50g, 60%); NMR (CDCIa) 6.58
(H-I'), 5.70 (2'), 6-18 (3'), 5.0-4-0 (4', 5' and 6'), 5.73
(5), 7-22 (6), 9.9 (NH), 6.59 (NH), 8.03 and 7-6 - 7.3
1"5,
J2,.8, = 10, J3,.4,---- 1"5", g4'.5'
= 9", Jl,.3,---- 1"5,
Jl'.4' ---- 1"5", J~'.4' = 1"5", Js.e = 8.
N-Thioacetylthiouracinine (23). To a soln of 22 (100
nag) in MeOH (54 mi) was added 1 N NaOH (25 ml), and
the mixture was allowed to stand at room temp until the
reaction was completed (monitored by TLC). It was then
neutralized with Amberlite IRC-50 (H+ form) and extrac-
ted repeatedly with M e O H - H 2 0 (1 : 1). The extract was
evaporated to dryness to give 23 (60 nag, 63%) as an amor-
phous solid; NMR (CD3OD) 6-06 (H-1 '), 5.98 (2'), 6"45
(3'), 5.68 (4'), 4.38 (5'), 6.55 (5), 7.55 (6), 2"55 (CHa-
(arom), Jz,.3, = 10, J5.6
= 8.
1- (4'-Acetamido-2' ,3' ,4'-trideoxy-fl-D-erythro-hex-2'-
enopyranosyl)uracil (18). The amide 17 was dissolved at
room temp in a MeOH sohi of0.1 M NaOMe (30 ml). After
12 hr the soln was neutralized with Amberlite IRC-50
(H + form) and evaporated to dryness to give crude amido-
alcohol 18 (1.3 g), which was crystallized from water as
needles, m.p. 202~. (Found: C, 51.46; H, 5.60; N, 15.16.
CnHmaNsO5 reqnires: C, 51.24; H, 5.38; N, 14-94%).
N-Acetyluracinine methyl ester (19). To a stirred soln
CS), Jz'.a'
=
10, J4'.5'
=
9", Js.e = 8.
Cytosinine dihydrochloride (2). The uracinine 23 (50
mg) and a saturated soin of ammonia in anhyd MeOH
of 18 (l.0g) in acetone-DMF (1:1, 200 ml) was added (12 mi) at - 5 ° were charged under anhyd conditions in a
stainless steel autoclave and heated at 100° for 40 hr.
After removal of the solvent, the residue was absorbed on
Amberlite IRA-410 (OH- form) and subsequently ehited
with 0-5 N HCI. The fractions which showed an UV ab-
sorption at 260 nm were combined, carefully evaporated
chromic anhydride (65 g) in small portions. During the
addition the temp was prevented from vigorous rising by
cooling with water and then the mixture was allowed to
stand at room temp for 30 min. It was then diluted with
MeOH and treated with an ether soln of a large excess of
diazomethane for 10min. After evaporation of the vola- to a small volume, and stored at 0", when crystalline 2 pre-
tile solvents at room temp under reduced pressure, the
residual soln was applied to a column of silica gel (500 g)
to remove chromium compounds, and the products were
eluted with C H ~ I r - M e O H (93:7). The eluents were
evaporated to dryness and purified by preparative TLC
to give 19 as an amorphous solid (460 mg, 42%); NMR
(CDCIs-CD3OD 1:I) 6-65 (H-I'), 5.95 (2'), 6.28 (3'),
cipitated; NMR (DO; DSS as standard) 6.64 (H-I'),
6.25 (2'), 6.50 (3'), 6.25 (5), 7.76 (6). This compound was
identified by comparison of its IR spectrum with the
authentic sample derived from blasticidin S?
Diacetylcytosinine methyl ester (24). (a) From 23.
Compound 23 (10 mg) was treated with methanolic am-
monia as described. After evaporation of the solvents, the
residue was directly acetylated with Ac~3 and pyridine
(1:2; 1.5 ml) at room temp overnight. After evaporation
of the solvent the product was dissolved in MeOH and
esterilied with an ether soln of excess diazomethane. The
mixture was evaporated in vacuo and separated by TLC
to give 24 (2.6 nag), which was crystallized from water as
needles, m.p. 267-268* (dec); UV (MeOH) 251 run (e
14200), 300 (5820); (MeOH-1 N HCI) 247 (8740), 309
(9300); ORD [~] (peak at 257nm)+3200 (dioxane-
EtOH 1 : 1); NMR (CDCIs-CDaOD 1: 1) 6-75 (H-I'),
6.00 (2'), 6.25 (3'), 5.00 (4'), 4.45 (5'), 7-63 (5), 8-02 (6),
3.80 (CHaO), 2.28 (CHACO), 2.00 (CHACO), Jva, = 1"5,
4.38 (5'), 5.90 (5), 7-58 (6), 3.80 (CHsO), 2.00 (CHACO),
J~'.a' ---- 10, J¢.s' = 9, Js~ = 8.
1-(4 '-Azido-2',3',4'-trideoxy-fl-D-hex-2'-enopyranosyl )-
uracil (20). The monobenzoate 16 (48 rag) was dissolved
in 0.04 M NaOMe in MeOH (5 mi) at room temp. After
2 hr, the sohi was neutralized with Amberlite IRC-50
(H + form) and evaporated to dryness. TLC separations
afforded 20 (22 rag) as an amorphous solid, NMR (CDCis)
6-58 (H-I'), 5-89 (2'), 6-38 ( 3 ' ) , 4 . 3 - 3 - 8 (4' and 5 ' ) , 4.60
and 4.58 (6'), 8.10 and 7.58 (arom), 5.75 (5), 7-25 (6),
Je.2,-- 1"5, Jz',s' = 10, J3'.¢ = 1"5, Jx,.s, = 1"5, J2'.¢ = 1"5,
J,.e = 8; IR (CHCIs) 2200 cm-1.
Methyl
1-(1 '-uracilyl)-4-azido-2,3,4-trideoxy-/3-D-
J~,a,
J 5 , 6 : 8.
= 10, Js,.¢ = 1"5, J4,.5, = 9, J l , a , = 1"5, J 1 , . 4 , = 1"5,
erythro-hex-2-enopyranuronate (21). Chromic anhydride
(600 rag) was added in small portions to a soln of 20 (10
rag) in acetone-DMF (1 : 1, 12 ml) at room temp during
30 min. The mixture was diluted with MeOH, treated with
excess diazomethane in ether, evaporated and extracted
with CHzCI~. TLC separations afforded the ester 21 as
an amorphous solid (9mg, 81%); NMR (CDCI3) 6.57
(H-l), 5-87 (2), 6.23 (3), 4.46 (4), 4-39 (5), 5.77 (5'), 7-12
(6'), 3.91 (CH~)); IR (KBr) 2200 cm-1.
Co) From blasticidin S. Cytosinine dihydrochioride
derived from blasticidin S was converted to 24 in the same
method as described above, m.p. 263-267° (dec); ORD
[O] (peak at 257 nm)+ 3400 (dioxane-EtOH 1 : 1);
UV (MeOH) 251 nm (e 14600), 300 (6060); (MeOH-1 N
HCI) 247 (9020), 309 (9580).
IR and NMR spectra of both diacetylcytosinine methyl
esters obtained from synthetic cytosinine and from blas-
ticidin S were superimposable each other.
N-Thioacetyithiouracinine methyl ester (22). P,S~
(1-17g) was added to a soln of 19 (447 mg) in anhyd pyri-
dine (120 ml), and the mixture was gently refluxed for I hr.
It was then evaporated to dryness and the residue was
dissolved in CH2CI~. After most of the excess P2S5 was
Acknowledgements-We thank Kaken Kagaku Co. Ltd.
for generous gift of blasticidin S.

1806
T. KONDO, H. NAKA1 and T. GOT(}
REFERENCES
~°K. A. Watanabe, I. Wempen and J. J. Fox, Chem.
Pharm. Bull. 18, 2368 (1970).
~S. Takeuchi, K. Hirayama, K. Ueda, H. Sakai and H.
Yonehara, J. Antibiotics IIA, 1 (1958); H. Yonehara,
S. Takeuchi, N. Otake, T. Endo, Y. Sakagami and Y.
Sumiki, Ibid. 16A, 195 (1963).
~r. Misato, I. Ishii, M. Asakawa, Y. Okimoto and K.
Fukunaga, Ann. Phytopath. Soc. Japan 24, 302
(1959).
~W. A. Bowles and R. K. Robins, J. Am. Chem. Soc.
86, 1256 (1964); J. J. K. Novfik and F. ~;orm, Col..
Czech. Chem. Commun. 27, 902 (1962).
t2T. Kondo, H. Nakai and T. Goto, Agr. Biol. Chem. 35,
1990 (1971).
13T. Kondo and T. Goto, Ibid. 35, 912 (1971).
~4See ref. 12.
3A. Hirai, S. G. Wildman and T. Hirai, Virology 36, 646
(1968).
15Cf. D. M. Ciment, R. J. Ferrier and W. G. Overend,
J. Chem. Soc. (C), 446 (1966).
~eE. J. Reist, R. R. Spencer, B. R. Baker and L. Goodman,
Chem. Ind., 1794 (1962); J. M. Williams and A. A.
Richardson, Tetrahedron 23, 1369 (1967).
~TCf. R. J. Ferrier and N. Vethaviyaser, J. Chem. Soc.
(C), 1907 (1971).
4N. Tanaka, Y. Sakagami, T. Nishimura, H. Yamaki and
H. Umezawa, J.Antibiotics 14A, 123 (1961).
5N. Otake, S. Takeuchi, T. Endo and H. Yonehara,
Tetrahedron Letters, 1405 (1965); Agr. Biol. Chem. 30,
126 (1966).
°N. Otake, S. Takeuchi, T. Endo and H. Yonehara,
Tetrahedron Letters, 1411 (1965); Agr. Biol. Chem. 30,
132(1966).
~SD. N. Kirk and M. A. Wilson, Chem. Commun. 64
(1970).
ell. Yonehara and N. Otake, Tetrahedron Letters 3785
(1966); see also J. J. Fox and K. A. Watanabe, Ibid.
897 (1966).
sS. Onuma, Y. Nawata and Y. Saito, Bull. Chem. Soc.
Japan 39, 1091 (1966).
~9H. Ohrui and S. Emoto, Agr. Biol. Chem. 32, 1371
(1968); K. A. Watanabe, I. Wempen and J. J. Fox,
Chem. Pharm. Bull. 18, 2368 (1970).
2°K. A. Watanabe, J. Beranek, H. A. Friedman and J. J.
Fox, J. Org. Chem. 30, 2735 (1965).
9C. L. Stevens, N. A. Nielsen and P. Blumbergs, J. Am.
Chem. Soc. 86, 1894 (1964).
2~G. Rosenkranz, O. Mancera, J. Gatica and C. Djerassi,
J. Am. Chem. Soc. 72, 4077 (1950).