Synthesis of acyclic adenine 8,N-anhydronucleosides

Article abstract of DOI:10.1135/cccc20001109

9-(4-Hydroxybutyl)adenine (10) was obtained by reaction of adenine with 4-[(2-tetrahydropyran-2-yl)oxy]butyl chloride (7) in the presence of DBU. 8-Bromo-9-(4-hydroxybutyl)adenine (13) was prepared by bromination of 10 or by alkylation of 8-bromoadenine (11) with 4-bromoethyl acetate followed by methanolysis. Tosylation of compound 13 afforded the 4-tosyloxy derivative 15 which gave on heating with methylamine or cyclopropylamine 6-methyl-(17a) or 6-cyclopropyl-7,8,9,10-tetrahydro-6H-[1,3]diazepino[1,2-e]purin-4-amine (17b), while the reaction with hydrazine afforded 7,8,9,10-tetrahydro-6H-[1,3]diazepino-[1,2-e]purine-4,6-diamine (17d). Treatment of compound 13 with thionyl chloride gave 9-(4-chlorobutyl)-8-chloroadenine (18) as the main product which was transformed to 17b, 6-propyl-7,8,9,10-tetrahydro-6H-[1,3]diazepino[1,2-e]purin-4-amine (17c) or 7,8,9,10-tetrahydro-6H-[1,3]diazepino[1,2-e]purin-4-amine (17e) by reaction with cyclopropylamine, propylamine or ammonia, respectively. Compound 17e was quite stable both in acid and alkaline solutions, at room temperature or at 90 °C. Compound 13 was converted to 9-(4-hydroxybutyl)-8-methylaminoadenine (19) by reaction with methylamine. Compound 19 failed to undergo intramolecular cyclization to diazepine 17a on treatment with diphenyl carbonate, bis(4-nitrophenyl) carbonate or 1,1′-carbonyldiimidazole.

Full text of DOI:10.1135/cccc20001109

Acyclic Adenine 8,N-Anhydro Nucleosides
1109
SYNTHESIS OF ACYCLIC ADENINE 8,N-ANHYDRONUCLEOSIDES
1,
2
Kateřina MESZÁROSOVÁ+,++, Antonín HOLÝ * and Milena MASOJÍDKOVÁ
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic,
1
2
166 10Prague 6, Czech Republic; e-mail: holy@uochb.cas.cz saman@uochb.cas.cz
Received March 1, 2000
Accepted Jun e 12, 2000
9-(4-Hydroxybutyl)aden in e (10) was obtain ed by reaction of aden in e with 4-[(2-tetrah ydro-
pyran -2-yl)oxy]butyl ch loride (7) in th e presen ce of DBU. 8-Brom o-9-(4-h ydroxybutyl)ade-
n in e (13) was prepared by brom in ation of 10 or by alkylation of 8-brom oaden in e (11) with
4-brom oeth yl acetate followed by m eth an olysis. Tosylation of com poun d 13 afforded th e
4-tosyloxy derivative 15 wh ich gave on h eatin g with m eth ylam in e or cyclopropylam in e
6-m eth yl- (17a) or 6-cyclopropyl-7,8,9,10-tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin -4-am in e
(17b ), wh ile th e reaction with h ydrazin e afforded 7,8,9,10-tetrah ydro-6H-[1,3]diazepin o-
[1,2-e]purin e-4,6-diam in e (17d ). Treatm en t of com poun d 13 with th ion yl ch loride gave
9-(4-ch lorobutyl)-8-ch loroaden in e (18) as th e m ain product wh ich was tran sform ed to 17b,
6-propyl-7,8,9,10-tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin -4-am in e (17c) or 7,8,9,10-tetra-
h ydro-6H-[1,3]diazepin o[1,2-e]purin -4-am in e (17e) by reaction with cyclopropylam in e,
propylam in e or am m on ia, respectively. Com poun d 17e was quite stable both in acid an d
alkalin e solution s, at room tem perature or at 90 °C. Com poun d 13 was con verted to
9-(4-h ydroxybutyl)-8-m eth ylam in oaden in e (19) by reaction with m eth ylam in e. Com poun d
19 failed to un dergo in tram olecular cyclization to diazepin e 17a on treatm en t with diph en yl
carbon ate, bis(4-n itroph en yl) carbon ate or 1,1′-carbon yldiim idazole.
Key w ord s: Nucleosides; Purin es; An h ydron ucleosides; Diazepin es; Acyclic n ucleoside an a-
logues; Cyclization s.
Acyclic n ucleoside an alogues attract atten tion m ain ly in m edicin al ch em is-
try as a structural class com prisin g several im portan t an tiviral drugs
(acyclovir an d its con gen er valaciclovir, gan ciclovir, buciclovir, pen ciclovir,
fem ciclovir, etc.)1. Our Laboratory h as been tradition ally perform in g sys-
tem atic study of acyclic n ucleosides bearin g cen tres of ch irality in th e side
ch ain s wh ich replace th e n ucleoside sugar residues. Am on g th ese com -
+ Part of M.S. Thesis. Ch arles Un iversity, Prague 2000.
++Presen t address: In stitute of Macrom olecular Ch em istry, Academ y of Scien ces of th e Czech
Republic, 162 06 Prague 6.
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1110
Meszárosová, Holý, Masojídková:
poun ds, in particular (S)-9-(2,3-dih ydroxypropyl)aden in e2 [(S)-DHPA] (m ar-
keted as an tih erpetic Duvira gel®), structurally related 3-(aden in -2-yl)-
2-h ydroxypropan oic acid3 (AHPA) an d group of eritaden in es4 attract m ost
atten tion . All th ese com poun ds in h ibit SAH h ydrolases5 an d h en ce exert ef-
fects on proliferative processes in volvin g SAM-depen den t m eth ylation s6.
(S)-DHPA causes sequen ce specific h ypom eth ylation of cytosin e con tain in g
triplets in plan t gen om es7. Th is m olecule is also paren t structure of acyclic
n ucleoside ph osph on ates (ANP): its 2-ph osph on om eth yl eth er, (S)-HPMPA,
is a powerful an tiviral8 an d also displays an tiparasitic activities again st
Plasmodium, Trypanosoma an d Leishmania spp.9.
In th e course of our studies on th e ch em istry an d biological effects of acy-
clic aden in e n ucleosides, we also in vestigated an alogues of purin e
cyclon ucleosides (“an h ydron ucleosides”) wh erein th e carboh ydrate m oiety
of th e n ucleoside is covalen tly lin ked to th e position 8 of th e purin e m ole-
cule10. Th e acyclic con gen ers, i.e., com poun ds in wh ich th e aliph atic ch ain
substitutin g th e h eterocyclic base at th e position N-9 is lin ked sim ulta-
n eously to th e C-8 via an eth er bridge, are form al an alogues of th e so-called
8,O-cyclon ucleosides. Our previous papers on such com poun ds described
th eir syn th esis an d properties11. Particularly in triguin g properties were re-
corded for 4′,8-an h ydro-9-(2,3-dih ydroxybutyl)aden in es an d th eir
2′,3′-O-isopropyliden e derivatives. Th e latter com poun ds exh ibited CD
spectra sim ilar to 5′,8-O-cycloaden osin e with m olar ellipticity even 30%
h igh er com pared with th is n ucleoside11. Th e com poun ds are four-rin g
fused system s (dioxolan e fused th rough diazepin e to purin e) deservin g an
in vestigation in view of diverse activities of such system s on DNA in teract-
in g en zym es. Th is con sideration brough t us to exam in e form ation an d sta-
bilities of system s an alogous to N-cyclon ucleosides, i.e. com poun ds
con tain in g th e seven -m em bered diazepin e rin g fused to th e purin e system .
Th is paper describes studies on th e com poun ds un substituted in th e
diazepin e rin g.
Two routes wh ich m igh t result in th e form ation of such com poun ds were
described in n ucleoside ch em istry: (i) in tram olecular rin g closure in volvin g
double n ucleoph ilic substitution of brom in e at 8-position of aden in e an d
O-tosylate situated at th e 4-position of th e side ch ain , by prim ary or sec-
on dary am in e (2) (Route A)12; (ii) in tram olecular rin g closure between
4-h ydroxy group of th e side ch ain an d 8-alkylam in o group in th e aden in e
(3) in th e presen ce of suitable activation agen ts (Route B)13. Th e th ird
m eth od14 wh ich con sists in (iii) in troduction of th e h ydroxyalkylam in o
group at th e C-8 of aden in e an d in tram olecular alkylation at N-9 (an d/or
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

Acyclic Adenine 8,N-Anhydro Nucleosides
1111
N-7) by th e action of an activatin g agen t was used in th e syn th esis of acy-
clic n ucleoside A from com poun d 4 (Route C) (Sch em e 1).
NH2
N
N
NHR
N
OH
N
NH2
NH2
(CH2)n
3
R
N
N
N
N
N
Br
N
B
OTs
N
H
N
N
(CH2)n
NH2
(CH2)n
X
2
4
A
C
R
N
N
N
N
N
(CH2)n
1
SCHEME 1
We h ave attem pted to sim plify Route A by direct syn th esis of
9-[4-(tosyloxy)butyl]aden in e by direct alkylation of aden in e with butan e-
1,4-diyl ditosylate (5). However, th is reaction perform ed in th e presen ce of
cesium carbon ate at elevated tem perature gave solely quatern ary tosylate 6
as a product of con secutive in tram olecular quatern ization of th e required
4-(tosyloxy)butyl in term ediate in position 3 of aden in e (Sch em e 2).
NH2
NH2
OTs
TsO
N
N
N
5
N
N
Cs2CO3
OTs
N
H
N
N
6
SCHEME 2
Hen ce, we exam in ed th e syn th esis of 8-brom o-9-(4-h ydroxybutyl)-
aden in e (13) as th e key com poun d for Route A. For preparation of
9-(4-h ydroxybutyl)aden in e (10) we applied th e already described11b reac-
tion sequen ce con sistin g in alkylation of aden in e with 4-brom obutyl ace-
tate an d subsequen t m eth an olysis of in term ediary acetate. For practical
reason s, we h ave also elaborated an altern ate syn th esis of com poun d 10:
4-ch lorobutan -1-ol was con verted to its tetrah ydropyran -2-yl eth er 7 by an
autocatalyzed reaction with dih ydropyran an d alkylation of aden in e with
th is com poun d in th e presen ce of DBU (ref.15) afforded th e protected deriv-
ative 8 alon g with th e m in or quan tity of th e correspon din g N3-isom er 9.
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1112
Meszárosová, Holý, Masojídková:
Acid h ydrolysis of com poun d 8 gave 9-(4-h ydroxybutyl)aden in e (10). Of
various varian ts of brom in ation reaction wh ich were described for aden in e
n ucleosides, brom in ation by brom in e water in acetate buffer16 (pH 4) was
th e m eth od of ch oice. It gave th e required 8-brom o derivative 13 in a good
yield (Sch em e 3).
NH2
NH2
OTHP
Cl
N
N
N
7
N
N
DBU
N
H
N
N
OTHP
8
H
NH2
N
NH2
N
N
N
N
N
N
N
OH
OR
10
9, R = OTHP
Br2
NH2
NH2
OAc
N
N
N
Br
N
N
Br
N
Br
K2CO3
N
H
N
N
OR
12, R = Ac
13, R = H
11
NH2
N
O
Br
THP =
N
N
14
Ac = COCH3
OH
SCHEME 3
An altern ative procedure for th e preparation of th e com poun d 13 m akes
use of alkylation of 8-brom oaden in e (13) with 4-brom obutyl acetate in th e
presen ce of potassium carbon ate in DMF. Th e startin g base was obtain ed by
reaction of aden in e with brom in e with out solven t (cf. ref.17). All attem pts
to perform th e brom in ation in solven ts such as DMF, dioxan e or eth ylen e
glycol dim eth yl eth er at low or elevated tem peratures failed. Th e alkylation
reaction took place on ly in DMF in th e presen ce of K2CO3 an d gave N9-iso-
m er 13 an d N3-isom er 14 in th e ratio 2 : 1, respectively (Sch em e 3). All
oth er varian ts, e.g. reagen t 7 in th e presen ce of NaH, Cs2CO3 or DBU, gave
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

Acyclic Adenine 8,N-Anhydro Nucleosides
1113
com plex m ixtures of products, wh ile treatm en t with ditosylate 5 in th e
presen ce of Cs2CO3 gave a polar product, eviden tly an an alogue of quater-
n ary salt 6. Tosylation of th e 4-h ydroxybutyl derivative 13 with tosyl ch lo-
ride in pyridin e gave th e required O-tosyl derivative 15 in a low yield.
An oth er product wh ich was isolated from th is reaction (com poun d 16)
arose eviden tly from th e tran sform ation of th e origin ally form ed 15 to th e
4-ch lorobutyl derivative an d its subsequen t N-tosylation (Sch em e 4). At-
tem pts to im prove th e yield of 15 such as by reducin g excess of tosyl ch lo-
ride, th e presen ce or absen ce of 4-(N,N-dim eth ylam in o)pyridin e, an d by
decreasin g th e reaction tem perature, failed.
NHTs
NH2
N
N
N
N
N
N
Br
Cl
N
N
Cl
Cl
16
18
R
NH2
NH2
NH2
N
R
N
N
N
N
N
R
NH2
17 a, R = methyl
b, R = cyclopropyl
c, R = propyl
d, R = NH2
N
N
Br
N
OTs
e, R = H
15
SCHEME 4
Treatm en t of com poun d 15 with prim ary am in es, such as m eth ylam in e
or cyclopropylam in e at elevated tem perature gave th e expected 6-m eth yl-
(17a) an d 6-cyclopropyl-7,8,9,10-tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin -
4-am in e (17b), respectively, in h igh yields as th e on ly reaction products.
Also h ydrazin e h ydrate in eth an ol, in an alogy to th e reaction described for
purin e N-an h ydron ucleosides18 gave 7,8,9,10-tetrah ydro-6H-[1,3]diazepin o-
[1,2-e]purin e-4,6-diam in e (17d ) as th e m ain reaction product (Sch em e 4).
In order to circum ven t th e low efficien cy of th is route to com poun ds 17
caused by th e in sufficien t yield of th e tran sform ation 13→15, we h ave in -
vestigated th e possibility of con vertin g th e h ydroxy group in com poun d 13
to th e 4-ch lorobutyl derivative by reaction with th ion yl ch loride. Sim ilar
con version s were described in th e literature19. Th e reaction proceeded
sm ooth ly; h owever, th e m ass spectrum dem on strated th at th e desired reac-
tion is accom pan ied by h alogen exch an ge at C-8. Th e m ajor com pon en t in
th e reaction product is 8-ch loro-9-(4-ch lorobutyl)aden in e (18) wh ile th e ex-
pected 8-brom o an alogue of com poun d 18 is presen t as a m in or com po-
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1114
Meszárosová, Holý, Masojídková:
n en t on ly. Non eth eless, crude 18 reacted as easily with m eth ylam in e or
propylam in e in th e sam e m an n er as th e tosyl derivative 15 to form th e
correspon din g 6-alkyl-7,8,9,10-tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin -
4-am in es 17a an d 17c. Most im portan tly, treatm en t of com poun d 18 with
m eth an olic am m on ia at elevated tem perature gave directly 7,8,9,10-tetra-
h ydro-6H-[1,3]diazepin o[1,2-e]purin -4-am in e (17e), th e paren t structure of
th e 7,8,9,10-tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin -4-am in e series. Th is
facile reaction with am m on ia con trasts with th e situation in cyclon ucleo-
side ch em istry wh ere in direct approach es (e.g., form ation of N-ben zylam in o
derivative followed by h ydrogen ation ) h ad to be used in order to prepare
th e N-un substituted 8,N-cyclon ucleoside20
.
Com poun d 17e resisted th e action of 0.1 or 1 M HCl, as well of 0.1 or 1 M
NaOH at room tem perature or 90 °C for 20 h . Th is stability con trasts with
th e com paratively easy an h ydro rin g open in g in structurally related acyclic
8,O-an h ydron ucleosides11.
An oth er approach to com poun ds 17 is based on th e in tram olecular
cyclization due to th e reaction of th e h ydroxy group in th e side ch ain an d
th e R–NH substituen t in th e position 8 in th e presen ce of activatin g agen ts,
such as diaryl carbon ates, 1,1′-carbon yldiim idazole or due to th e
Mitsun obu reaction . Th e approach h as been used in n ucleoside ch em istry
leadin g to satisfactory yields20. Th e startin g 9-substituted 8-(m eth yl-
am in o)aden in e derivative 19 was obtain ed from th e 8-brom o derivative 13
by treatm en t with m eth ylam in e. Th e reaction of com poun d 19 with di-
ph en yl carbon ate or 1,1′-carbon yldiim idazole even at elevated tem perature
did n ot proceed at all. Replacem en t of diph en yl carbon ate by bis(4-n itro-
ph en yl) carbon ate afforded traces of 4′-O-(4-n itroph en yl) carbon ate on ly.
No form ation of com poun d 17a was observed in an y of th e above experi-
m en ts. It is n ot th e first case wh ere th e reaction proceedin g easily with n u-
cleosides fails with th eir acyclic n ucleoside coun terparts. Eviden tly, it is
a rath er fixed con form ation of th e n ucleoside m olecule wh ich stron gly
favours suitable m utual orien tation of th e substituen t at C-8 of th e base
an d a h ydroxy group of th e sugar m oiety, wh ich plays a very im portan t
role in in tram olecular reaction s leadin g to cyclon ucleosides. Such a con for-
m ation is eviden tly less favoured in N-alkyl derivatives with sp3 con figura-
tion of all carbon atom s of th e side ch ain .
We h ave also tried to tran sform th e h ydroxy group in com poun d 19 to
its tosylate with th e aim to form th e seven -m em bered rin g in such a com -
poun d by th e action of a stron g base (e.g. DBU). However, com poun d 20
was th e on ly product isolated from th e com plex tosylation m ixture. It origi-
n ates eviden tly from th e expected tosylate by in tram olecular alkylation
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

Acyclic Adenine 8,N-Anhydro Nucleosides
1115
at N-3 (sim ilar to th e form ation of com poun d 6) an d subsequen t
N6-tosylation (Sch em e 5).
NH2
NTs
NH2
N
N
N
N
N
N
CH3NH2
TsCl
N
N
N
Br
NHCH3
NHCH3
OH
N
N
N
OH
13
19
20
(PhO)2CO; (4-O2NPhO)2CO
or im2CO
17a
SCHEME 5
Th e ultim ate approach to th e N-cyclon ucleosides m akes use of an appro-
priate 8-[N-(4-h ydroxybutyl)-N-m eth ylam in o]aden in e (23) as th e key com -
poun d. Th is sh ould be th en con verted to a reactive in term ediate capable of
N-alkylatin g th e h eterocyclic base. N-Meth yl-N-[4-(tetrah ydropyran -2-yl)-
oxybutyl]am in e (21) was obtain ed by h eatin g 4-[(2-tetrah ydropyran -
2-yl)oxy]butyl ch loride (7) with m eth ylam in e in eth an ol. Treatm en t of
8-brom oaden in e (11) with com poun d 21 on h eatin g in DMF gave a com -
plex m ixture from wh ich som e expected 8-substituted in term ediate 22
could be isolated in a very low yield. It was furth er processed to th e
4-h ydroxybutyl derivative 23. However, th e m ain product of th is reaction is
8-dim eth ylam in oaden in e (24) (Sch em e 6). Th us, th e reactivity of th e sec-
on dary am in e 21 with respect to brom in e attach ed to th e purin e skeleton is
very low, m uch lower th an th e reactivity of th e DMF solven t.
NH2
NH2
NH2
NHCH3
THPO
CH3
N
N
N
21
N
N
N
Br
N
N(CH3)2
+
N
H
N
H
N
H
N
N
N
RO
11
24
O
22, R = THP
23, R = H
THP =
SCHEME 6
Th e structures of com poun ds described in th is paper were assign ed by
m ean s of “attach ed proton test” an d proton -coupled 13C NMR spectra.
Ch aracteristic alkylation effects (upfield sh ift ca –8 ppm at C-2 an d lowfield
sh ift ca 12 ppm at C-8) were observed in th e 13C NMR spectrum of com -
1
poun d 14; th e splittin g of C-2 doublet (δ 144.54, J(C-2,H-2) = 209.0) in th e
proton -coupled spectrum by two H-1′ atom s (3J(C-2,H-1′) = 4.9) eviden ces its
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1116
Meszárosová, Holý, Masojídková:
N3-alkyl structure; in th e N9-isom er 13, th e splittin g occurs at C-8 (δ 126.42).
Th e in tram olecular cycle form ation in com poun d 17a is ch aracterized in
th e proton -coupled spectrum by doublet of triplets of C-4 (δ 150.72,
3
3J(C-4,H-2) = 11.7, J(C-4,H-1′) = 3.9) and by broad m ultiplet of C-8 (δ 156.94,
W = 26 Hz); th is m ultiplet is n arrowed (C-8, δ 152.54, W = 19.5 Hz) in com -
3
poun d 19, due to th e absen ce of J(C-8,H-4′). Th e in tram olecular alkylation
at N-3 in com poun d 20 was con firm ed by th e observed upfield sh ifts at C-2
an d C-4 (ca –10 ppm ) an d by th e m ultiplicity of carbon sign als in th e pro-
ton -coupled NMR spectrum . Th e doublet at δ 153.86 correspon ds to C-6
(3J(C-6,H-2) = 10.7), th e m ultiplet at δ 152.59 (W = 15 Hz) to C-8, th e dou-
blet of triplets at δ 141.60 to C-2 (1J(C-2,H-2) = 211.9, 3J(C-2,H-4′) = 2.9),
3
th e pen tet at δ 140.51 (3J(C-4,H-1′) = J(C-4,H-4′) = 3.9) to C-4 an d th e sin -
glet at δ 122.23 to C-5.
Th e results obtain ed in th is study dem on strate th at th e acyclic seven -
m em bered N-cyclon ucleoside an alogues can be effectively prepared by con -
certed in tram olecular reaction of 9-[(4-tosyloxy)butyl] or 9-(4-ch lorobutyl)
derivatives of 8-brom o- or 8-ch loroaden in e in th e presen ce of am m on ia or
prim ary am in es. Th e seven -m em bered system is stable both un der stron gly
alkalin e an d stron gly acidic con dition s.
EXPERIMENTAL
Meth ods
Com poun ds were dried at 13 Pa over ph osph orus pen toxide. Meltin g poin ts were deter-
m in ed on a Kofler block an d are un corrected. TLC on silica gel was perform ed on Silufol UV
254 plates in th e followin g system s: ch loroform –m eth an ol (9 : 1, S1), ch loroform –m eth an ol
(85 : 15, S2), ch loroform –m eth an ol (4 : 1, S3), ch loroform –m eth an ol (3 : 7, S4), water–
eth an ol–aceton e–eth yl acetate (1 : 1 : 1 : 4, S5), propan -2-ol–con cen trated aqueous
am m on ia–water (7 : 1 : 2, S6). Preparative loose-layer ch rom atograph y was perform ed with
silica gel con tain in g UV in dicator (Kavalier Votice, Czech Republic) on plates 40 × 17 × 0.4 cm .
Colum n ch rom atograph y was don e with silica gel (30 µm ) obtain ed from th e sam e source.
Preparative RP-HPLC was perform ed on a Beckm an n Prep 350 apparatus usin g 300 × 40 m m
colum n s of Separon SGX-RPS 10µ (C18). Paper electroph oresis was perform ed on Wh atm an
No. 1 paper at 20 V/cm (1 h ) in 0.02 M sodium tetraborate. Th e m obility (EUp) is related to
uridylic acid. Deion isation on Dowex 50 was don e with 100–150 m l colum n s of th e resin in
H+ form prewash ed with water. After application of th e m ixture, th e colum n was first
wash ed with water un til th e acidity of th e eluate an d its UV absorption (m on itored by
Uvicord 4 701 A, LKB, Sweden at 254 n m ) dropped, an d th en with dilute (1 : 10) aqueous
am m on ia. Th e UV-absorbin g fraction was evaporated in vacuo. 1H NMR spectra (δ, ppm ;
J, Hz) were m easured on a Varian UNITY-200 (200 MHz) or Varian UNITY-500 (500 MHz) in
h exadeuteriodim eth yl sulfoxide with tetram eth ylsilan e as in tern al stan dard. 13C NMR spec-
tra (δ, ppm ) were m easured on Varian UNITY-500 (125.7 MHz) an d ch em ical sh ifts are refer-
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

Acyclic Adenine 8,N-Anhydro Nucleosides
1117
en ced to th e solven t sign al (δ(CD3SOCD3) 39.7 ppm ). UV absorption spectra were m easured
on a Beckm an DU-65 apparatus. Mass spectra were m easured on a ZAB-EQ (VG An alytical,
Man ch ester, U.K.) m ass spectrom eter. Ion ization was perform ed with FAB tech n ique (ion iza-
tion Xe, acceleration voltage
8 kV). Sam ples in m eth an ol were applied to th e
th ioglycerol–glycerol m atrix (3 : 1).
Materials
Aden in e, butan e-1,4-diol, 4-ch lorobutan -1-ol, 4-brom obutyl acetate, 4-(dim eth ylam in o)-
pyridin e, m eth ylam in e an d dim eth ylam in e solution in eth an ol, h ydrazin e h ydrate,
cyclopropylam in e, propylam in e, diph en yl carbon ate, bis(4-n itroph en yl) carbon ate,
1,1′-carbon yldiim idazole an d DBU were purch ased from Sigm a–Aldrich Prague (Czech
Republic); brom in e, cesium carbon ate, tosyl ch loride, dih ydropyran an d th ion yl ch loride
were products of Fluka (Germ an y). DMF was distilled in vacuo from ph osph orus pen toxide
an d kept over m olecular sieves (1A).
Butan e-1,4-diyl Ditosylate (5)
Butan e-1,4-diol (4.5 g, 50 m m ol) was added dropwise un der stirrin g to a solution of tosyl
ch loride (23.3 g, 122.2 m m ol) in pyridin e (100 m l), th e m ixture was kept at 0 °C for 3 h an d
left to stan d overn igh t in a refrigerator. Water (20 m l) was added an d th e m ixture was taken
down in vacuum to approxim ately 2/3 of th e origin al volum e. Water (40 m l) was added an d
th e m ixture was extracted with eth yl acetate (four 50 m l portion s). Th e organ ic layer was
wash ed with water (50 m l), th en with 1 M HCl un til th e extract rem ain ed acidic an d fin ally
with water. Th e volatiles were th en evaporated in vacuo an d th e residue codistilled with
toluen e. Ch rom atograph y on a silica gel colum n (300 m l) in th e system toluen e–eth yl
acetate followed by crystallization from m eth an ol afforded 13.8 g (69%) of ditosylate 5,
m .p. 68 °C; ref.20 gives m .p. 65–68 °C (m eth an ol). For C18H22O6S2 (398.4) calculated:
54.25% C, 5.56% H, 16.09% S; foun d: 54.42% C, 5.64% H, 15.84% S.
∆8-4,5,6,7-Tetrah ydro[1,3]diazepin o[1,2,3-cd]purin -11-am in e Tosylate (6)
Aden in e (2.7 g, 20 m m ol) an d cesium carbon ate (10 m m ol) in DMF (70 m l) were h eated
at 80 °C for 1 h an d tosylate 5 (10 g, 25 m m ol) was added in on e portion . Th e m ixture
was stirred at 100 °C un der exclusion of m oisture. Th e m ixture dissolved an d a crystallin e
m aterial gradually precipitated. After 6 h at 100 °C, th e m ixture was cooled, th e product was
filtered off, wash ed successively with water, aceton e an d eth er, an d dried to afford com -
poun d 6. Yield 2.7 g (37%), n ot m eltin g below 280 °C, EUp = –0,55. For C16H19N5O3S (361.4)
calculated: 53.17% C, 5.30% H, 19.38% N, 8.87% S; foun d: 52.92% C, 5.40% H, 19.33% N,
9.01% S. 1H NMR: 9.20 brs, 1 H an d 9.10 brs, 1 H (NH2); 8.63 s, 1 H an d 8.36, 1 H (H-2 an d
H-8); 7.48 d, 2 H an d 7.10 d, 2 H (arom . H); 4.55 t, 2 H an d 4.45 t, 2 H, J(CH2,CH2) = 5.6
(N-CH2); 2.28 s, 3 H (arom . CH3); 2.20 m , 2 H an d 2.13 m , 2 H (C-CH2).
4-[(2-Tetrah ydropyran -2-yl)oxy]butyl ch loride21 (7)
4-Ch lorobutan -1-ol (50 m l) in dich lorom eth an e (270 m l) was treated at 0 °C with dih ydro-
pyran (65 m l). After th e exoth erm ic reaction h as subsided, 4.5 M HCl in DMF (1.5 m l) was
added an d th e reaction was kept at 0 °C for 30 m in an d at room tem perature for 2 days.
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1118
Meszárosová, Holý, Masojídková:
A saturated NaHCO3 solution (200 m l) was added, th e organ ic ph ase was separated, th e
aqueous ph ase was extracted with ch loroform (2 × 100 m l), th e com bin ed extracts were
wash ed with water (2 × 50 m l), dried with an h ydrous MgSO4 an d evaporated. Th e residue
gave on distillation (b.p. 86–87 °C/2 kPa) 86.5 g (89.4%) of com poun d 7 (ca 90% pure by
GC). For C9H17ClO2 (192.7) calculated: 56.10% C, 8.89% H, 18.40% Cl; foun d: 56.74% C,
8.95% H, 17.66% Cl. 1H NMR: 4.54 m , 1 H (O-CH-O); 3.66 t, 2 H, J = 6.6 (CH2-Cl); 3.72 m
an d 3.42 m , 2 × 1 H (O-CH2); 3.64 t and 3.36 t, 2 × 1 H, J = 6.5, 6.5, 9.8 (O-CH2); 1.75 m and
1.63 m , 2 × 2 H an d 1.48 m , 4 H (C-CH2). MS (FAB), m/z (rel.%): 193 (20) [M + H]+.
9-[(4-Tetrah ydropyran yloxy)butyl]aden in e (8) an d 3-[(4-Tetrah ydropyran yloxy)butyl]-
aden in e (9)
A m ixture of aden in e (6 g, 44.4 m m ol) an d DBU (7.1 m l) in 70 m l DMF was h eated at 100 °C
for 30 m in an d com poun d 7 (10 m l, 54.7 m m ol) was added. Th e reaction m ixture was
stirred at 100 °C for 4 h un der exclusion of m oisture, DMF was evaporated in vacuo an d
codistilled with toluen e (two 25 m l portion s). Th e residue in ch loroform (200 m l) was ex-
tracted with water (50 m l), th e organ ic layer was dried with an h ydrous MgSO4, filtered an d
evaporated. Th e residue was purified by colum n ch rom atograph y on silica gel in a ch loro-
form –eth an ol m ixture. Yield 7.38 g (57%) of th e N9-isom er 8 an d 1.42 g (11%) of th e N3-iso-
m er 9. Com poun d 8, m .p. 58 °C, RF 0.61 (S2). For C14H21N5O2 (291.4) calculated: 57.72% C,
7.26% H, 24.04% N; foun d: 57.61% C, 7.06% H, 23.78% N. 1H NMR: 8.15 s an d 8.14, 2 ×
1 H (H-2 an d H-8); 7.20 brs, 2 H (NH2); 4.50 m , 1 H (O-CH-O); 4.17 t, 2 H, J(1′,2′) = 7.1
(H-1′); 3.69 m , 1 H an d 3.62 m , 1 H an d 3.39 m , 1 H an d 3.33 m , 1 H (O-CH); 1.86 m , 2 H
an d 1.68 m , 1 H an d 1.58 m , 1 H an d 1.52–1.40 m , 6 H (C-CH). 13C NMR: 156.17 (C-6);
152.57 (C-2); 149.77 (C-4); 141.05 (C-8); 118.97 (C-5); 98.16 (O-C-O); 61.47 (C-4′); 42.96
(C-1′); 30.45 (C-3′); 26.70 (C-2′); 66.26, 26.57, 25.21 an d 19.35 [CH2(THP)]. MS (FAB), m/z
(rel.%): 292.2 (65) [M + H]+. Com poun d 9, m .p. 154 °C, RF 0.42 (S2). For C14H21N5O2
(291.4) calculated: 57.72% C, 7.26% H, 24.04% N; foun d: 57.44% C, 7.29% H, 23.54% N. 1H
NMR: 8.35 s, 1 H (H-8); 7.96 brs, 1 H an d 7.82 brs, 1 H (NH2); 7.75 s, 1 H (H-2); 4.50 m , 1 H
(O-CH-O); 4.32 t, 2 H, J(1′,2′) = 7.1 (H-1′); 3.69 m , 1 H an d 3.61 m , 1 H an d 3.38 m , 1 H an d
3.33 m , 1 H (O-CH2); 1.95 m , 2 H an d 1.67 m , 1 H an d 1.57 m , 1 H an d 1.52–1.40 m , 6 H
(C-CH2). 13C NMR: 155.13 (C-6); 152.67 (C-8); 149.88 (C-4); 143.45 (C-2); 120.72 (C-5);
98.15 (O-C-O); 61.45 (C-4′); 43.36 (C-1′); 30.43 (C-3′); 25.98 (C-2′); 66.31, 26.41, 25.19 an d
19.34 [CH2(THP)]. MS (FAB), m/z (rel.%): 292.2 (100) [M + H]+.
9-(4-Hydroxybutyl)aden in e (10)
Com poun d 8 (7 g, 24.0 m m ol) was refluxed un der stirrin g for 30 m in in 20% aqueous m eth -
an ol (450 m l) with Dowex 50 (H+-cycle) (30 m l). Th e suspen sion was filtered, wash ed succes-
sively with m eth an ol an d with ca 3% m eth an olic am m on ia solution , th e com bin ed filtrates
were evaporated an d th e residue was crystallized from eth an ol. Yield 4.53 g (91%) of com -
poun d 10. M.p. 198–200 °C, RF = 0.37 (S5). For C9H13N5O (207.2) calculated: 52.16% C,
6.32% H, 33.79% N; foun d: 51.94% C, 6.29% H, 33.63% N. 1H NMR: 8.145 s, 1 H an d
8.14 s, 1 H (H-2 an d H-8); 7.23 brs, 2 H (NH2); 4.46 t, 1 H, J(OH,4′) = 4.9 (OH); 4.14 t, 2 H,
J(1′,2′) = 7.1 (H-1′); 3.39 dt, 2 H, J(4′,3′) = 6.6 (H-4′); 1.82 m , 2 H (H-2′); 1.37 m , 2 H (H-3′).
MS (FAB), m/z (rel.%): 208 (100) [M + H]+.
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

Acyclic Adenine 8,N-Anhydro Nucleosides
8-Brom oaden in e (11)
1119
Brom in e (30 m l, 0.59 m ol) was cautiously poured on to aden in e (10 g, 74 m m ol) in 500 m l
flask (CAUTION! Vigorous reaction!) an d th e m ixture was left to stan d 3 h in a stoppered
flask. Th e excess brom in e was th en left to evaporate in th e h ood. Th e residue was stirred in
water (≈100 m l), alkalized with con cen trated aqueous am m on ia to dissolution an d th e alka-
lin e solution was n eutralized by addition of acetic acid. Th e precipitated crude product was
filtered off, wash ed with water an d boiled un der stirrin g with water (250 m l). Th is suspen -
sion was filtered wh ile h ot, th e precipitate was wash ed with water, aceton e an d eth er, an d
dried in vacuo. Yield 9.5 g (59.7%) of com poun d 13, m .p. >250 °C, RF 0.40 (S2). For
C5H4BrN5 (214.0) calculated: 28.06% C, 1.88% H, 37.33% Br, 32.72% N; foun d: 27.79% C,
1.95% H, 36.68% Br, 32.27% N. 1H NMR: 13.70 br, 1 H (NH); 8.10 s, 1 H (H-2); 7.44 brs, 2 H
(NH2). MS (FAB), m/z (rel.%): 215.1 (8) [M + H]+.
8-Brom o-9-(4-h ydroxybutyl)aden in e (13)
Method A: By bromination of 9-(4-hydroxybutyl)adenine. 4-(Hydroxybutyl)aden in e (10; 10 g,
48.4 m m ol) was dissolved by sligh t h eatin g in water (200 m l), an equal volum e of 0.5
M
CH3COONa/acetic acid buffer (pH 4) was added an d saturated aqueous brom in e (5 m l,
96.6 m m ol brom in e) solution was added dropwise un der stirrin g. Th e stirrin g was con tin ued
at room tem perature for 6 h , a saturated NaHSO3 solution was added un til th e discoloration
disappeared an d th e pH of th e m ixture was set to 6–7 with con cen trated NaOH solution .
Th e m ixture was evaporated, codistilled with eth an ol an d th e residue was extracted with
ch loroform in a Soxh let apparatus for 16 h . Th e crude extract was purified by silica gel
ch rom atograph y an d crystallized from water. Yield 10 g (72%) of a sligh tly yellow product
13, m .p. 208 °C, RF 0.50 (S2). For C9H12BrN5O (286.1) calculated: 37.78% C, 4.34% H,
27.93% Br, 24.48% N; foun d: 37.43% C, 4.25% H, 27.93% Br, 23.99% N. 1H NMR: 8.13 s,
1 H (H-2); 7.38 brs, 2 H (NH2); 4.44 t, 2 H, J(OH,H) = 5.1 (OH); 4.13 t, 2 H, J(1′,2′) = 7.3
(H-1′); 3.39 t, 2 H (H-4′); 1.78 m , 2 H an d 1.40 m , 2 H (H-3′ an d H-2′). 13C NMR: 154.92
(C-6); 152.96 (C-2); 150.93 (C-4); 126.42 (C-8); 119.16 (C-5); 60.29 (C-4′); 43.86 (C-1′); 29.64
(C-3′); 25.91 (C-2′). MS (FAB), m/z (rel.%): 288 (90) [M + H]+.
Method B: By alkylation of 8-bromoadenine with 4-bromobutyl acetate. 8-Brom oaden in e (11;
0.5 g, 2.32 m m ol) an d potassium carbon ate (0.64 g, 4.6 m m ol) in DMF (5 m l) was stirred at
135 °C for 30 m in . 4-Brom obutyl acetate (0.68 g, 3.50 m m ol) was added an d th e m ixture
h eated at th is tem perature for an oth er 8 h . Th e solven t was stripped in vacuo an d th e resi-
due was codistilled with toluen e. Th e crude product was extracted with m eth an ol, th e fil-
trate evaporated in vacuo an d th e residue was separated by loose-layer TLC. Th e ban ds were
eluted with m eth an ol, evaporated an d th e residues treated with 0.1 M sodium m eth an olate
in m eth an ol (1 h ); after n eutralization with Dowex 50, th e m ixtures were evaporated
in vacuo. Subsequen t crystallization of th e products from eth an ol gave 0.3 g (44.8%) of
N9-isom er 13 (iden tical with th e product obtain ed by m eth od A) an d 0.15 g (22.4%) of th e
N3-isom er 14, m .p. 208 °C, RF 0.50 (S2), respectively. 1H NMR: 8.40 s, 1 H (H-2); 8.17 brs,
2 H (NH2); 4.26 t, 2 H, J(1′,2′) = 7.1 (H-1′); 3.40 t, 2 H, J(4′,3′) = 7.4 (H-4′); 1.88 m , 2 H an d
1.40 m , 2 H (H-3′ an d H-2′). 13C NMR: 153.67 (C-6); 149.52 (C-4); 144.54 (C-2); 138.22
(C-8); 120.90 (C-5); 60.30 (C-4′); 49.60 (C-1′); 29.38 (C-3′); 25.70 (C-2′).
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1120
Meszárosová, Holý, Masojídková:
Tosylation of 8-Brom o-9-(4-h ydroxybutyl)aden in e (13)
Crystallin e tosyl ch loride (18.6 g, 97.6 m m ol) was added un der stirrin g to an ice-cool solu-
tion of com poun d 13 (14 g, 48.9 m m ol) an d 4-(N,N-dim eth ylam in o)pyridin e (100 m g) in
pyridin e (170 m l), th e solution was stirred at 0 °C for 3 h an d left to stan d overn igh t in a re-
frigerator. Water (200 m l) was added an d th e solution was left in refrigerator for addition al
3 h . Th e precipitate was filtered off, wash ed with eth er an d dried in vacuo. Yield 2.37 g
(11%) of 8-brom o-9-[4-(tosyloxy)butyl]aden in e (15), m .p. 149 °C, RF 0.81 (S2). For
C
16H19BrN5O3S (441.2) calculated: 43.65% C, 4.12% H, 18.15% Br, 15.91% N, 7.28% S;
foun d: 42.02% C, 4.06% H, 18.65% Br, 15.62% N, 7.42% S. 1H NMR: 8.10 s, 1 H (H-2); 7.74 d
an d 7.44 d, 2 × 2 H (arom . H); 7.39 brs, 2 H (NH2); 4.06 t, 2 H, J = 7.0 an d 4.04 t, 2 H, J =
6.3 (H-1′an d H-4′); 2.40 s, 3 H (CH3-arom .); 1.71 m an d 1.55 m , 2 × 2 H (H-2′ an d H-3′). MS
(FAB), m/z (rel.%): 441.9 (100) [M + H]+.
Th e filtrate was evaporated an d th e residue codistilled with water. Th e residue in water
(100 m l) was repeatedly extracted with ch loroform an d eth yl acetate. Th e com bin ed extracts
were dried with an h ydrous MgSO4, filtered, an d th e solven ts were taken down in vacuo.
Th e residue afforded 8-brom o-9-(4-ch lorobutyl)-6-(tosylam in o)purin e (16) (0.24 g; 15.1%),
m .p. 176 °C, RF 0.96 (S2). For C16H17BrClN5O2S (458.8) calculated: 41.89% C, 3.73% H,
17.42% Br, 7.73% Cl, 15.27% N, 6.99% S; foun d: 41.81% C, 3.89% H, 18.20% Br, 7.92% Cl,
14.93% N, 6.72% S. 1H NMR: 12.80 br, 1 H (NH); 8.35 brs, 1 H (H-2); 7.86 m , 2 H an d
7.37 d, 2 H (arom . H); 4.19 t, 2 H, J(1′,2′) = 6.8 (H-1′); 3.64 t, 2 H, J(4′,3′) = 6.3 (H-4′); 2.36 s,
3 H (CH3-arom .); 1.87 m , 2 H an d 1.70 m , 2 H (H-2′ an d H-3′). MS (FAB), m/z (rel.%): 460
(30) [M + H]+.
8-Ch loro-9-(4-ch lorobutyl)aden in e (18)
Com poun d 13 (2.15 g, 7.5 m m ol) in ch loroform (25 m l) was treated un der stirrin g with
DMF (0.25 m l) an d SOCl2 (13 m l, 21.2 g, 0.18 m ol). Th e resultin g solution was refluxed for
3 h , taken down in vacuo, th e residue was dissolved in m eth an ol, n eutralized with aqueous
am m on ia an d evaporated. Th e residue was triturated with eth er, filtered off, dried (5.2 g)
an d used with out purification for furth er reaction s with am in es. MS (FAB), m/z (rel.%): 260
(100) [M + H] [C9H1235Cl2N5 (260.1)]; 170 (25) [BH].
6-Meth yl-7,8,9,10-tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin -4-am in e (17a)
Method A: Com poun d 15 (1.4 g, 3.17 m m ol) in 30% eth an olic m eth ylam in e (50 m l) was
h eated in an autoclave at 100 °C for 2 days. Th e reaction m ixture was evaporated, th e resi-
due was dissolved in ch loroform an d extracted with water. Th e ch loroform layer was dried
with an h ydrous MgSO4, filtered an d evaporated. Crystallization from eth an ol afforded th e
title com poun d 17a (0.67 g; 97%), m .p. 262–263 °C, RF 0.39 (S2). For C10H14N6 (218.3) cal-
culated: 55.03% C, 6.47% H, 38.50% N; foun d: 55.23% C, 6.33% H, 38.80 N. 1H NMR:
7.98 s, 1 H (H-2); 6.63 brs, 2 H (NH2); 4.01 m an d 3.13 m , 2 × 2 H (H-1′ an d H-4′); 3.01 s,
3 H (N-CH3); 1.89 m , 2 H an d 1.77 m , 2 H (H-2′ an d H-3′). 13C NMR (APT): 156.94 (C-8);
153.32 (C-6); 150.72 (C-4); 149.91 (C-2); 116.445 (C-5); 53.96 (C-4′); 42.76 (C-1′); 41.215
(CH3); 29.47 an d 26.34 (C-2′ an d C-3′). UV (m eth an ol), λm ax (εm ax): 277.5 (18 305). MS
(FAB), m/z (rel.%): 219.1 (100) [M + H]+.
Method B. Th e dried crude 4-ch lorobutyl derivative 18 (1.5 g) was h eated in 30%
eth an olic m eth ylam in e (50 m l) in an autoclave at 100 °C for 10 h . Th e solution was evapo-
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

Acyclic Adenine 8,N-Anhydro Nucleosides
1121
rated an d th e residue was deion ized on Dowex 50 (H+-form ) (100 m l) an d th e am m on ia
eluate was evaporated in vacuo. Th e residue, on purification by silica gel colum n ch rom atog-
raph y in ch loroform –m eth an ol, gave com poun d 17a. Yield 0.22 g (46.5%).
6-Cyclopropyl-7,8,9,10-tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin -4-am in e (17b)
A m ixture of 8-brom o-9-[4-(tosyloxy)butyl]aden in e (15; 0.250 g, 0.57 m m ol), eth an ol
(20 m l) an d cyclopropylam in e (0.5 m l, 7.1 m m ol) was h eated in an autoclave at 100 °C for
2 days. After evaporation an d codistillation of th e residue with eth an ol, th e crude product
was purified on silica gel colum n (100 m l) in th e system ch loroform –m eth an ol. Yield 0.087
g (63%) of com poun d 17b , m .p. 250 °C, RF 0.58 (S4). For C12H16N6 (244.3) calculated:
59.00% C, 6.60% H, 34.40% N; foun d: 47.14% C, 6.05% H, 22.98% N. 1H NMR: 7.99 s, 1 H
(H-2); 6.70 brs, 2 H (NH2); 3.94 m , 2 H (H-1′); 3.24 m , 2 H (H-4′); 2.86 m , 1 H (N-CH);
1.80 m an d 1.70 m , 2 × 2 H (H-2′ an d H-3′); 0. 72 m an d 0.48 m , 2 × 2 H (C-CH2). MS (FAB),
m/z (rel.%): 245.18 (100) [M + H]+.
6-Propyl-7,8,9,10-tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin -4-am in e (17c)
Th e dried crude 4-ch lorobutyl derivative 18 (0.4 g) in an eth an ol–propylam in e m ixture
(1 : 1, 40 m l) was h eated in an autoclave at 100 °C for 2 days, evaporated an d codistilled
with eth an ol. After desaltin g on Dowex 50 (H+-form ), purification of th e residue by silica gel
colum n ch rom atograph y in ch loroform –m eth an ol an d crystallization from ch loroform , com -
poun d 17c (41 m g, 28.8%) was isolated. M.p. 181–182 °C, RF 0.54 (S2). For C12H18N6 (246.3)
calculated: 58.52% C, 7.37% H, 34.12% N; foun d: 55.83% C, 7.33% H, 32.37% N. 1H NMR:
7.96 s, 1 H (H-2); 6.54 brs, 2 H (NH2); 4.01 m , 2 H (H-1′); 3.40 t, 2 H, J(1′′,2′′) = 7.3 (H-1′′);
3.22 m , 2 H (H-4′); 1.83 m , 4 H (H-2′ an d H-3′); 1.65 sext, 2 H, J(2′′,1′′) = J(2′′,3′′) = 7.3
(H-2′′); 0.90 t, 3 H, J(3′′,2′′) = 7.3 (H-3′′). MS (FAB), m/z (rel.%): 247.1 (100) [M + H]+.
6-Am in o-7,8,9,10-tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin e-4,6-diam in e (17d )
Hydrazin e h ydrate (3 m l, 103 m m ol; 98%) was added to a suspen sion of 8-brom o-9-[4-
(tosyloxy)butyl]aden in e (15; 300 m g, 0.68 m m ol) in eth an ol (15 m l) an d th e m ixture was
stirred at room tem perature for 3 days un til th e startin g com poun d disappeared (th e reac-
tion course was followed by TLC in S5). Th e h eterogen eous reaction m ixture was evaporated
to dryn ess an d excess h ydrazin e was rem oved by codistillation with eth an ol. Th e resultin g
m ixture was desalted on Dowex 50 (H+-cycle) an d th e product purified by preparative
reverse ph ase ch rom atograph y. Yield of com poun d 17d , 52 m g (35%; after crystallization
from eth an ol). M.p. 242 °C, RF 0.28 (S1). For C9H13N7·2H2O (255.3) calculated: 42.35% C,
6.71% H, 38.41% N; foun d: 42.54% C, 6.31% H, 37.64% N. 1H NMR: 8.01 s, 1 H (H-2);
6.76 brs an d 4.92 brs, 2 × 2 H (NH2); 4.00 m , 2 H (H-1′); 3.29 m , 2 H (H-4′); 1.91 m an d
1.72 m , 2 × 2 H (H-2′ an d H-3′). MS (FAB), m/z (rel.%): 220.1 (100) [M + H]+.
7,8,9,10-Tetrah ydro-6H-[1,3]diazepin o[1,2-e]purin -4-am in e (17e)
Th e dried crude 4-ch lorobutyl derivative 18 (2.5 g) was h eated at 120 °C with saturated
m eth an olic am m on ia (50 m l) in an autoclave for
3 days. After evaporation an d
codistillation with eth an ol th e crude reaction product was desalted on Dowex 50 (H+-form ),
adsorbed from m eth an olic solution on silica gel an d purified by colum n ch rom atograph y on
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

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Meszárosová, Holý, Masojídková:
th e sam e sorben t in ch loroform –m eth an ol. Crystallization from m eth an ol afforded com -
poun d 17e (0.41 g; 55.6% ), m .p. 237 °C, RF 0.27 (S1), 0.47 (S2). For C9H12N6 (204.2) calcu-
lated: 52.93% C, 5.92% H, 41.15% N; foun d: 52.50% C, 5.76% H, 40.85% N. 1H NMR:
7.96 s, 1 H (H-2); 6.61 t, 1 H, J(NH,4′) = 3.4 (NH); 6.53 brs, 2 H (NH2); 3.98 brt, 2 H,
J(1′,2′) = 5.0 (H-1′); 3.06 brtd, 2 H, J(4′,NH) = 3.4, J(4′,3′) = 5.0 (H-4′); 1.80 m , 4 H (H-2′ an d
H-3′). MS (FAB), m/z (rel.%): 205.2 (100) [M + H]+.
Stability of Com poun d 17e in Acid an d Alkali
Th e stability was studied in 0.1 an d 1 M solution s of HCl or NaOH, respectively. Th e m ix-
tures were kept at room tem perature overn igh t an d/or h eated at 90 °C. Sam ples were taken
after 1, 4 an d 20 h an d an alyzed by TLC in th e system S2. No form ation of rin g-open in g
products was observed un der an y of th e above con dition s.
9-(4-Hydroxybutyl)-8-(m eth ylam in o)aden in e (19)
8-Brom o-9-(4-h ydroxybutyl)aden in e (13) (1.0 g, 3.5 m m ol) in 30% m eth ylam in e solution in
eth an ol (50 m l) was h eated at 100 °C in an autoclave for 3 days. Th e m ixture was evapo-
rated, th e residue deion ized on a colum n (50 m l) with Dowex 50 (H+-form ) an d fin ally
purified by colum n (150 m l) ch rom atograph y on siliga gel in ch loroform –m eth an ol. Yield
0.57 g (69%) of com poun d 19, m .p. 205 °C, RF 0.30 (S3). For C10H16N6O (236.3) calculated:
50.83% C, 6.83% H, 35.57% N; foun d: 50.13% C, 6.94% H, 34.40% N. 1H NMR: 7.89 s, 1 H
(H-2); 6.66 q, 1 H, J(NH,CH3) = 4.6 (NH); 6.36 brs, 2 H (NH2); 4.43 t, 1 H, J(OH,4′) = 5.1
(OH); 3.91 t, 2 H, J(1′,2′) = 7.2 (H-1′); 3.38 td, 2 H, J(4′,OH) = 5.1, J(4′,3′) = 6.5 (H-4′); 2.90 d,
3 H, J(CH3,NH) = 4.6 (N-CH3); 1.64 m , 2 H an d 1.38 m , 2 H (H-2′ an d H-3′). 13C NMR (APT):
152.54 (C-8); 152.08 (C-6); 150.51 (C-4); 148.81 (C-2); 116.99 (C-5); 60.55 (C-4′); 40.32
(C-1′); 29.72 (C-2′); 29.27 (CH3); 25.40 (C-3′). MS (FAB), m/z (rel.%): 237.1 (100) [M + H]+.
Attem pts on Cyclization of 9-(4-Hydroxybutyl)-8-(m eth ylam in o)aden in e (19) (cf. ref.22
)
a) With diphenyl carbonate: A m ixture of com poun d 19 (23.6 m g, 0.1 m m ol), diph en yl car-
bon ate (32.1 m g, 0.15 m m ol) an d trieth ylam in e (90.6 µl, 65.8 m g, 0.65 m m ol) in DMF (1.5
m l) was stirred at 135 °C for 24 h . TLC in S3 did n ot detect an y ch an ge of com poun d 19 un -
der th ese con dition s.
b) With bis(4-nitrophenyl) carbonate and triethylamine: A m ixture of com poun d 19 (23.6 m g,
0.1 m m ol), bis(4-n itroph en yl) carbon ate (45.6 m g, 0.15 m m ol) an d trieth ylam in e (83.6 µl,
60.7 m g, 0.60 m m ol) in DMF (1.5 m l) was stirred at 135 °C for 24 h . TLC in S3 detected
4′-O-(4-n itroph en yl) ester (givin g a yellow spot in am m on ia vapour); n o form ation of com -
poun d 17a was observed.
c) With bis(4-nitrophenyl) carbonate and DBU: A m ixture of com poun d 19 (23.6 m g, 0.1
m m ol), bis(4-n itroph en yl) carbon ate (45.6 m g, 0.15 m m ol) an d DBU (0.60 m m ol) in DMF
(1.5 m l) was stirred at 135 °C for 16 h . TLC in S3 did n ot detect form ation of com poun d
17a. Min or form ation of a 4′-O-(4-n itroph en yl) ester (givin g a yellow spot in am m on ia
vapour) was observed by TLC an alysis. Major part of com poun d 19 rem ain ed un ch an ged.
d) W ith 1,1′-carbonyldiimidazole: A m ixture of com poun d 19 (23.6 m g, 0.1 m m ol),
1,1-carbon yldiim idazole (24.3 m g, 0.15 m m ol) in DMF (0.6 m l) was stirred at 135 °C for
20 h. TLC in S3 did not detect form ation of com pound 17a, nor other change of com pound 19.
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

Acyclic Adenine 8,N-Anhydro Nucleosides
1123
N-Meth yl-11-(tosylim in o)-4,5,6,7-tetrah ydro-11H-[1,3]diazepin o[1,2,3-cd]purin -2-am in e (20)
Tosyl ch loride (0.81 g, 4.23 m m ol) was added in on e portion un der stirrin g at 0 °C to a solu-
tion of com poun d 19 (0.5 g, 2.12 m m ol) an d 4-(dim eth ylam in o)pyridin e (26 m g, 0.212
m m ol) in pyridin e (20 m l). Th e m ixture was stirred at 0 °C for addition al 3 h an d left over-
n igh t in a refrigerator. Water (20 m l) was th en added, th e reaction m ixture was taken down
n early to dryn ess in vacuo an d codistilled with toluen e (3 portion s). Th e residue was
deion ized on a colum n (100 m l) of Dowex 50 (H+-form ) an d th en purified by preparative
HPLC in water to afford wh ite crystallin e com poun d 20 (0.095 g; 12%), m .p. >250 °C, RF
0.64 (S6). For C17H20N6O2S·2H2O (408.5) calculated: 49.99% C, 5.92% H, 20,57% N,
7.85% S; foun d: 49.44% C, 5.92% H, 20.85% N, 8.12% S. 1H NMR: 8.05 s, 1 H (H-2); 7.72 d,
2 H an d 7.21 d, 2 H (arom . H); 6.95 brq, 1 H, J(NH,CH3) = 4.5 (NH); 4.35 m , 2 H (H-1′);
4.01 m , 2 H (H-4′); 2.87 d, 3 H, J(CH3,NH) = 4.5 (N-CH3); 2.31 s, 3 H (CH3-Ts); 2.09 m an d
2.03 m , 2 × 2 H (H-2′ an d H-3′). 13C NMR (APT): 153.86 (C-6); 152.59 (C-8); 142.86
(C-arom .); 141.595 (C-2); 140.51 (C-4); 140.13, 128.43 an d 127.09 (C-arom .); 122.23 (C-5);
51.58 (C-4′); 44.19 (C-1′); 29.41 (N-CH3); 25.32 an d 25.24 (C-2′ an d C-3′); 21.10 (CH3). UV
(m eth an ol), λm ax (εm ax): 319.5 (16 028). MS (FAB), m/z (rel.%): 373.2 (100) [M + H]+.
N-Meth yl-N-[4-(tetrah ydropyran -2-yloxy)butyl]am in e (21)
Com poun d 7 (25 g, 0.13 m ol) in eth an olic m eth ylam in e solution (8 M, 70 m l, 0.56 m ol) was
h eated in an autoclave at 100°C for 6 h . Th e m ixture was cooled to 0 °C, filtered an d wash ed
with eth er; th e filtrate was evaporated in vacuo. Trieth ylam in e (1 m l) was added to th e crude
residue an d distilled in vacuo to afford 19.6 g (80.8%) of colourless 21, b.p. 86–90 °C/20 Pa.
1H NMR: 4.51 m , 1 H (O-CH-O); 3.72 m an d 3.41 m , 2 × 1 H (OCH2); 3.60 br, 1 H (NH);
3.60 dt an d 3.31 dt, 2 × 1 H, J = 6.5, 6.5, 9.6 (O-CH2); 2.43 t, 2 H, J = 6.9 (N-CH2); 2.24 s,
3 H (N-CH3); 1.70 m an d 1.58 m , 2 × 1 H an d 1.55–1.40 m , 6 H (C-CH2). MS (FAB), m/z
(rel.%): 188 (100) [M + H]+.
Reaction of 8-Brom oaden in e (11) with Com poun d 21
8-Brom oaden in e (11; 1 g, 4.67 m m ol) was dissolved by h eatin g in DMF (25 m l) at 110 °C
an d com poun d 21 (2.174 g, 11.68 m m ol) was added. Th e m ixture was stirred at 125 °C for
2 days un til th e startin g m aterial disappeared an d th en stripped in vacuo. Th e residue
was codistilled with toluen e (2 × 25 m l). Ch rom atograph y on loose-layer of silica gel in
m eth an ol–ch loroform (1 : 3) system gave two fraction s wh ich were furth er purified on silica
gel colum n s in ch loroform –m eth an ol. Th e less polar, oran ge colored oil gave by precipita-
tion with eth er from a m in im um of eth an ol 284 m g (19%) of am orph ous 8-[N-m eth yl-N-
(4-tetrah ydropyran yloxy)butylam in o]aden in e (22), RF 0.93 (S2). 1H NMR: 8.12 s, 1 H (H-2);
6.92 brs, 2 H (NH2); 4.53 dd, 1 H, J = 2.8 an d 4.6 (O-CH-O); 3.71 m an d 3.40 m , 2 × 1 H
(O-CH2); 3.64 dt an d 3.36 dt, 2 × 1 H, J = 6.5 an d 6.5 an d 9.8 (O-CH2); 3.40 t, 2 H, J = 7.1
an d 7.1 (N-CH2); 3.07 s, 3 H (N-CH3); 1.73–1.35 m , 8 H (C-CH2). MS (FAB), m/z (rel.%):
321.4 (40) [M + H]+, 237.3 (100) [M – THP + H]+. HR MS (FAB) for C15H25N6O2 (MH) calcu-
lated: 321.2039, foun d: 321.1990.
On passin g of an aqueous solution of com poun d 22 (190 m g, 593 µm ol) th rough
a
Dowex 50 colum n (H+-form , 20 m l) an d evaporation of th e UV-absorbin g eluate gave
8-[N-m eth yl-N-(4-h ydroxybutylam in o)aden in e] (23; 130 m g; 93%), m .p. 191–192 °C, RF 0.64
(S2). For
C10H16N6O·H2O (254.3) calculated: 47.23% C, 7.13% H, 33.03% N; foun d:
Collect. Czech. Chem. Commun. (Vol. 65) (2000)

1124
Meszárosová, Holý, Masojídková:
46.99% C, 7.12% H, 30.70% N. 1H NMR: 11.80 br, 1 H (NH); 7.92 s, 1 H (H-2); 6.21 brs, 2 H
(NH2); 4.45 brs, 1 H (OH); 3.45 t, 2 H an d 3.43 t, 2 H, J = 6.4 (N-CH2 an d O-CH2); 3.02 s,
3 H (N-CH3); 1.59 m an d 1.42 m , 2 × 2 H (C-CH2). MS (FAB), m/z (rel.%): 237.3 (100) [M + H]+.
Purification of th e m ain reaction product obtain ed from loose-layer plate ch rom atograph y
on silica gel colum n followed by crystallization from m eth an ol gave 8-(N,N-dim eth ylam in o)-
aden in e (24), 520 m g (62.6%), m .p. >250 °C, RF 0.80 (S2). For C7H10N6 (178.2) calculated:
47.18% C, 5.66% H, 47.16% N; foun d: 46.19% C, 5.67% H, 45.80% N. 1H NMR: 12.0 br, 1 H
(NH); 8.14 s, 1 H (H-2); 6.98 brs, 2 H (NH2); 3.09 s, 6 H (2 × CH3). MS (FAB), m/z (rel.%):
179.5 (100) [M + H]+.
This study was supported by the Grant Agency of the Czech Republic (grant No. 203/96/K001) and
by Gilead Sciences (Foster City (CA), U.S.A.). Our thanks are due to the staff of Mass Spectrometry
Laboratory (Dr K. Ubik, Head) and to the Analytical Laboratory (Dr V. Pechanec, Head), both of this
Institute. Valuable discussions with Dr Z. Janeba and excellent assistance of Ms B. Nováková are
greatly appreciated.
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