Synthesis of cyclic N-nitrourethanes by the simultaneous oxidative desulfurization and nitration of cyclic thiourethanes

Article abstract of DOI:10.1002/jhet.862

The reaction of five- and six-membered cyclic thiourethanes with acetyl nitrate results in a vigorous reaction that generates copious amounts of red-brown nitrogen oxide fumes and produces the corresponding cyclic N-nitrourethanes in high yields (>95%). The overall yield of the cyclic N-nitrourethanes starting from an aminoalcohol using the " thiourethane" route is superior to the conventional route going through the cyclic urethane. Copyright

Full text of DOI:10.1002/jhet.862

March 2012
Synthesis of Cyclic N-Nitrourethanes by the Simultaneous
Oxidative Desulfurization and Nitration of Cyclic Thiourethanes
421
Rodney L. Willer,* Christopher G. Campbell, and Robson F. Storey
School of Polymers and High Performance Materials, The University of Southern Mississippi,
118 College Drive #5050, Hattiesburg, Mississippi 39406
*E-mail: rodney.willer@usm.edu
Received November 3, 2010
DOI 10.1002/jhet.862
Published online 23 November 2011 in Wiley Online Library (wileyonlinelibrary.com).
The reaction of five- and six-membered cyclic thiourethanes with acetyl nitrate results in a vigorous
reaction that generates copious amounts of red–brown nitrogen oxide fumes and produces the corre-
sponding cyclic N-nitrourethanes in high yields (>95%). The overall yield of the cyclic N-nitrour-
ethanes starting from an aminoalcohol using the ‘‘thiourethane’’ route is superior to the conventional
route going through the cyclic urethane.
J. Heterocyclic Chem., 49, 421 (2012).
INTRODUCTION
thesized from the analogous spirodithiourethane, 2a, using
basic hydrogen peroxide desulfurization [5] (Scheme 1).
The yield for the conversion of 2a to 2b is very poor
(44%) and the procedure is somewhat lengthy [5].
Cyclic N-nitrourethanes (N-nitrocarbamates) are well
known compounds. First reported by Franchimont and
Lubin in 1902 [1], they were originally synthesized by
the nitration of the corresponding cyclic urethanes with
fuming nitric acid. These compounds were extensively
studied by White et al. [2] in the mid-1960s, and they
introduced the use of acetyl nitrate as the nitrating agent
[2]. Modern syntheses of cyclic N-nitrourethanes involve
reaction of the trimethylsilyl derivatives of the cyclic
urethanes with dinitrogen pentoxide in methylene chlo-
ride [3]. In the course of our work on energetic com-
pounds, we selected 3,8-dinitro-1,6-dioxa-3,8-diazaspir-
o[4.4]nonane-2,7-dione, 1, as a target molecule, because
it is calculated to be dense (d ¼ 1.88 g/cc) and energetic
[4]. Herein we report a new synthetic approach to 1 and
related compounds involving simultaneous oxidative
desulfurization and nitration of cyclic thiourethanes
using acetyl nitrate.
There is limited literature precedence describing the
nitration chemistry of cyclic thiourethanes. Thus, we
examined the reaction of 2a with an acetyl nitrate solu-
tion at ꢀ10ꢁC as a possible alternative. Surprisingly, a
vigorous reaction occurred with the evolution of copious
amounts of nitrogen oxides. Upon work-up, the product was
1
identified as the desired spirodinitrourethane, 1, based on H
NMR, 13C NMR, FT-IR, and high resolution mass spectros-
copy data (Fig. 1). The structure was confirmed by X-ray
crystallography [6]. The yield of 1 was greater than 95%.
We examined the scope of this tandem process by
studying the reaction of the four monocyclic thiour-
ethanes, 3–6 (Scheme 2), with acetyl nitrate. The cyclic
thiourethanes were synthesized using a procedure simi-
lar to that reported by Li and Ohtani [7]. Reaction of
these four compounds with an acetyl nitrate solution
produced high yields (>95%) of the corresponding
cyclic N-nitrourethanes, 7–10. Formation of high yields
of 10 did require a increase of the reaction temperature
to 0ꢁC.
The synthesis of both the monocyclic urethanes and
thiourethanes starts from the corresponding aminoalco-
hols (Scheme 2). Typical yields reported for the synthe-
sis of the five- and six-membered cyclic urethanes from
the aminoalcohol and diethyl carbonate range from 40
to 70% [2]. The yields reported by Li and Othani (and
RESULTS AND DISCUSSION
The standard approach to 1 would be nitration of the
known
1,6-dioxa-3,8-diazaspiro-[4.4]nonane-2,7-dione
[5], 2b, with acetyl nitrate. Compound 2b has been syn-
C
V
2011 HeteroCorporation

422
R. L. Willer, C. G. Campbell, and R. F. Storey
Vol 49
Scheme 1. Synthesis of 2a and 2b.
Figure 1. Reaction of 2a with acetyl nitrate.
confirmed by this work) for the corresponding thiour-
ethanes are in the range of 80–95%. It can be easily
seen that the ‘‘thiourethane’’ route to the cyclic N-nitro-
urethanes appears to be superior to the ‘‘conventional’’
urethane route.
equipped with a stir bar [7]. The solution is stirred at 0ꢁC,
while carbon disulfide (7.62 g, 0.10 mol) is added dropwise.
The solution is stirred at room temperature for 30 min. Hydro-
gen peroxide (30%, 16–20 mL, 0.15–0.2 mol) is then added at
such a rate that reflux of the solvent was observed and until
the upper solution of the reaction mixture no longer becomes
cloudy by addition of extra hydrogen peroxide. The reaction is
cooled to room temperature and then filtered. The methanol
and water are removed by reduced pressure. The residue is
extracted with methylene chloride (2 ꢂ 100 mL). The com-
bined methylene chloride extracts are washed with water (2 ꢂ
50 mL) and then dried over MgSO4. The organic layer is fil-
tered and then evaporated to dryness under reduced pressure.
1,3-Oxazolidine-2-thione, 3. The compound was recrystal-
lized from benzene to give colorless crystals, mp 97–98ꢁC
(ref. 7; 97–99ꢁC).
5-Methyl-1,3-oxazolidine-2-thione, 4. The compound was
recrystallized from benzene to give colorless crystals, mp 73–
74ꢁC (ref. 7; 74.5–75ꢁC).
4-Ethyl-1,3-oxazolidine-2-thione, 5. The compound was
recrystallized from water to give colorless crystals, mp 74–
75ꢁC (ref. 8; 74–75ꢁC).
Tetrahydro-1,3-oxazine-2-thione, 6. The compound was
recrystallized from benzene to give colorless crystals, mp 127–
128ꢁC (ref. 7; 128–129ꢁC).
EXPERIMENTAL
Materials. Reagents and all specialty solvents (anhydrous,
NMR) were purchased from Aldrich Chemical Co. and used
without further purification. Routine solvents were purchased
from Fisher Scientific.
Instrumentation. FT-IR spectra were obtained on a Bruker
Equinox 55 spectrometer as KBr pellets or films. High resolu-
tion mass spectroscopy (HR MS) analyses were conducted at
The University of Iowa HRMSF. 1H NMR and 13C NMR
spectra were obtained using a Varian Mercury NMR spectrom-
eter operating at a frequency of 300.13 MHz for proton and
75.5 MHz for carbon. DSCs were obtained on a TA Instru-
ments Model Q200 using hermetically sealed Al pans under a
nitrogen purge. They were run from ambient to 300ꢁC at 3ꢁC/
min.
1,6-Dioxa-3,8-diazaspiro[4.4]nonane-2,7-dithione, 2a. This
General procedure for the reaction of cyclic thiour-
ethanes with acetyl nitrate. A dry 50-mL round-bottom flask
maintained at ꢀ10ꢁC (brine/ice bath) and under a nitrogen
atmosphere is charged with 4.08 g (4.0 mL) of acetic anhy-
dride. Slow addition of 2.52 g (1.60 mL) of 100% nitric acid
forms the acetyl nitrate solution. The temperature is raised to
¨
compound was made by the procedure of Koll and coworkers
[5]. The melting point (mp) was 205–206ꢁC (ref. 5; 206ꢁC).
General procedure for 2-thioxo-1,3-O,N-heterocycles, 3–6
(cyclic thiourethanes). Modified Li and Ohtani procedure
[7]. The 2-aminoalcohol (0.1 mol), triethylamine (0.1 mol),
and methanol (100 mL) are placed in a two-neck 250-mL flask
Scheme 2. Synthesis of cyclic N-nitrourethanes via the urethane and thiourethane routes.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

March 2012
Synthesis of Cyclic N-Nitrourethanes by the Simultaneous Oxidative Desulfurization
and Nitration of Cyclic Thiourethanes
423
10ꢁC for 10 min and then lowered back to ꢀ10ꢁC. The cyclic
thiourethane (5.0 mmol) is added in two portions, resulting in
the immediate generation of a red/brown gas. The reaction is
stirred for 1 h and allowed to come to 0ꢁC. The volatiles are
removed under high vacuum at room temperature. The crude
product is washed with cold distilled water, collected, and
dried. The crude products were dissolved in a minimum
amount of acetone, filtered, and the acetone allowed to evapo-
rate overnight to give the crystalline product.
In the cases of the liquid compounds (8 and 9), the crude
compounds were taken up in 20 mL of ethyl acetate and
washed with saturated sodium bicarbonate solution until neu-
tral. The ethyl acetate solution was dried over MgSO4, filtered,
and the solvent removed to give the compounds.
1456(m), 1392(m), 1357(sh), 1337(sh), 1285(s), 1171(s),
1056(s), 955(m), 880(m), 827(m), 727(sh), 742(m) cmꢀ1. HR
MS (EI) ; C4H6N2O4: calcd. 146.0328; found 146.0324 amu.
3-Nitro-4-ethyl-1,3-oxazolidine-2-one, 9. This compound is
a liquid.
1H NMR(CD3CN): d ¼ 0.95(t, J ¼ 7.5 Hz, 3H, ACH3),
1.85(p, J ¼ 7.5 Hz, 2H, ACH2) 4.14(dxd, J ¼ 9.0 Hz, J ¼ 7.5
Hz, 1H, H5), 4.52(t, J ¼ 9.0 Hz, 1H, H5), 4.69(m, 1H, H4)
ppm.13C NMR(CD3CN)):
57.96(C4), 66.07(C5), 149.01(C2) ppm. FT-IR(film)
2976(w), 2884(w), 1817(vs), 1577(s), 1285(s), 1262(sh),
1163(s), 1120(sh), 1057(w), 1015(w), 832(m), 760(w), 738(w),
740(sh) cmꢀ1. HR MS (EI); C5H8N2O4: calcd. 160.0484;
found 160.0478 amu.
d
¼
7.67(CH3), 24.08(CH2),
¼
3,8-Dinitro-1,6-dioxa-3,8-diazaspiro[4.4]nonane-2,7-dione,
1. Caution: This compound calculates to be a moderate explo-
sive [4] and should be handled with due caution until adequate
safety data are available! DSC: Strong exothermic decomposi-
tion at 187ꢁC.
3-Nitro-tetrahydro-1,3-oxazine-2-one, 10. The compound
was recrystallized from methanol to give colorless crystals, mp
75–76ꢁC (ref. 1; 75ꢁC).
Acknowledgments. This work was supported by the Office of
Naval Research (Dr. Clifford Bedford) (N00014081006). The
authors gratefully acknowledge Dr. Damon Parrish for providing
the X-ray crystal structure of 1, which will be published in a
related article.
1H NMR(acetone-d6): d ¼ 4.92(d, J ¼ ꢀ11.1 Hz, 1H),
5.29(d, J ¼ ꢀ11.1Hz, 1H) ppm. 13C NMR(acetone -d6): d ¼
67.27(C4,6), 76.37(C5), 145.16(C2,7
)
ppm. FT-IR(KBr)
¼
3048(w), 2986(w), 2915(w), 1836(vs), 1816(vs), 1598(vs),
1471(m), 1407(m), 1392(m), 1319(s), 1277(s), 1245(s),
1200(s), 1184(s), 1164(s), 1130(s), 1118(s), 1097(s), 1067(s),
1054(s), 976(m), 850(m), 828(m), 786(m), 753(m), 729(s),
707(m), 634(m) cmꢀ1. HR MS (EI); C5H4N4O8 [M]þ: calcd.
248.0029; found 248.0034 amu.
REFERENCES AND NOTES
[1] Franchimont, A. P. N.; Lubin, A. Rec Trav Chim 1902, 21,
45.
3-Nitro-1,3-oxazolidine-2-one, 7. The compound was re-
crystallized from acetone to give colorless crystals, mp 110–
111ꢁC (ref. 1; 111ꢁC).
[2] White, E. H.; Chen, M. C.; Dolak, L. A. J Org Chem 1965,
31, 3038.
3-Nitro-5-methyl-1,3-oxazolidine-2-one, 8. This compound
is a liquid.
[3] Millar, R. W.; Philbin, S. P. Tetrahedron 1997, 53, 4371.
[4] Willer, R. L. J Mex Chem Soc 2009, 53, 107.
1H NMR(CD3CN): d ¼ 1.42(d, J ¼ 7.0 Hz, 3H, ACH3),
3.95(t, J ¼ 7.0 Hz, 1H, H4), 4.40(t, J ¼ 7.0 Hz, 1H, H4), 4.78
(hex, J ¼ 7.0 Hz, 1H, H5) ppm. 13C NMR(CD3CN): d ¼
19.37(CH3), 51.82(C4), 70.43(C5), 148.30(C2) ppm. FT-
IR(film) ¼ 2990(w), 2940(w), 1809 (vs), 1573(vs), 1479(m),
´
[5] Saul, R.; Kern, T.; Kopf, J.; Pinter, I.; Koll, P. Eur J Org
¨
Chem 2000, 205.
[6] Parrish, D. Naval Research Laboratory, unpublished data.
[7] Li, G.; Ohtani T. Heterocycles 1997, 45, 2471.
[8] Rosen, A. A. J Am Chem Soc 1952, 74, 2994.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet