P. Singh, A. Singh / Tetrahedron Letters 54 (2013) 2525–2527
2527
O
phase processes is very similar to the working of natural processes
(high voltage/temperature conditions in the atmosphere arise dur-
ing lightening, etc.), there is possibility that adenine might have
formed through a similar route during the prebiotic period.
H O
2
CO2
+
NH3
CH COONH4
H N
2
NH2
3
Acknowledgments
NH2
NH2
N
O
Financial assistance from CSIR, New Delhi and DST, New Delhi is
gratefully acknowledged. A.S. thanks DST, New Delhi for fellow-
ship. Contributions of Professor A. S. Brar in creating state of the
art research facilities are gratefully acknowledged.
N
N
HN
N
H
HO
N
NH
N
N
O
1
Supplementary data
Scheme 1. Plausible route of formation of adenine from ammonium acetate.
Supplementary data (mass spectra, NMR spectra) associated
NH2
N
NH
2
H
N
N
N
N
N
References and notes
N
H
1
N
H
N
N
N
N
NH2
1.
2.
3.
Saladino, R.; Botta, G.; Pino, S.; Costanzo, G.; Mauro, E. D. Chem. Soc. Rev. 2012,
1, 5526–5565. and references therein.
Ponnamperuma, C.; Lemmon, R. M.; Mariner, R.; Calvin, M. Proc. Natl. Acad. Sci.
U.S.A. 1963, 49, 737–740.
, Adenine
6, Pyrazoloadenine
7, 2-Aminopurine
4
NH2
Miller, S. L. J. Am. Chem. Soc. 1955, 77, 2351–2361. and references therein.
H
N
H
N
N
4. Ring, D.; Wolman, Y.; Friedmann, N.; Miller, S. L. Proc. Natl. Acad. Sci. U.S.A.
972, 69, 765–768.
Powner, M. W.; Gerland, B.; Sutherland, J. D. Nature 2009, 459, 239–242.
N
N
1
H N
2
N
5.
N
N
6. Cleaves, H. J., II; Scott, A. M.; Hill, F. C.; Leszczynski, J.; Sahai, N.; Hazen, R. Chem.
Soc. Rev. 2012, 41, 5502–5525. and references therein.
8
, Zarzissine
9, 1H-Pyrazolo[4,3-d]pyrimidin-7-amine
7.
Watson, J. T.; Sparkman, O. D. Introduction to Mass Spectrometry—
Instrumentation, Applications, and Strategies for Data Interpretation, 4th ed.;
John Wiley and Sons, 2007. and references therein.
Chart 2.
8
9
.
.
Gaskell, S. J. J. Mass Spectrom. 1997, 32, 677–688.
Fenn, J. B.; Mann, M.; Meng, C. K.; Wong, S. F.; Whitehouse, C. M. Science 1989,
2
46, 64–71.
primitive earth conditions, here formation of adenine from CO
NH in the presence of water is confirmed. In addition to Ponn-
amperuma’s observation of increased adenine yield on reducing
2
and
1
1
0. Krase, N. W.; Gaddy, V. L. J. Ind. Eng. Chem. 1922, 14, 611–615.
1. Salvan, C. M.; Yaseli, R. M. Chem. Soc. Rev. 2012, 41, 5404–5415. and references
therein.
3
2
H
2
percentage (increased oxidizing conditions) and Lemmon’s
12. Lemmon, R. M. Chem. Rev. 1970, 70, 95–109.
1
3. Experimental procedure: mass spectra were recorded on a Bruker MicroTof QII
mass spectrometer. As per requirement (mentioned in the text), electrospray
ionization (ESI) or atmospheric pressure chemical ionization (APCI) (direct
probe) method was used, operating the machine in a +ve mode. The source
temperature was kept at 180 °C. The capillary voltage was 4500 V and vacuum
experiments of formation of only adenine under primitive earth
1
2
conditions, the present experiments also show the formation of
adenine under oxidizing conditions (C as CO ).
Even after accepting all the above observations of correct mass
and isotopic pattern of adenine, indicating its formation from CO
NH and H O, the compounds corresponding to mass of adenine
2
À7
was maintained at 5–6 Â 10 mbar. All the solvents used here were of HPLC
2
,
grade and purchased from Sigma–Aldrich.
10/20 mM solutions of CH
were prepared in ACN–H
spectrometer through a syringe keeping the flow rate at 180
were processed in Bruker DaltoniK Data Analysis 4.0 software. For LC–MS, the
Dionex Ultimate 3000 HPLC was linked to a mass spectrometer using Hystar3.2
software. 5
using ACN–H
Data Analysis 4.0 and Target analysis 1.2.
For the solution phase reaction, ammonium acetate (1 g) was taken in 50 ml
water. The solution was refluxed for 72 h and concentrated under vacuum. The
solid residue was washed with acetone and dried for further investigations.
The reaction in sealed tube was performed by just moistening the ammonium
acetate with water and heating at 150 °C for 70–80 h.
3
COONH
O/ACN–D
4
, NaHCO
3
, NH
O and injected into the mass
L/h. Mass spectra
4 3 4 4 3
NO , NH NCS and NH HCO
3
2
2
2
O (3:7)/H
2
were also searched from the database using target analysis (Bruker
Target analysis 1.2). The search identified five compounds (1, 6–9;
l
Chart 2) with same molecular formula C
5 6 5
H N (M+H), mass
l
L of sample was run through C8 column with a flow rate 0.2 ml
O (20:80) as eluent. Data were processed in Bruker DaltoniK
1
36.0618 (error, ppm 0.0), isotopic pattern (mSigma 2.3) and
1
13
2
retention time 7.6 min. H and C NMR spectral data (Table S1,
Figs. S5 and S6) helped to identify adenine amongst other isomeric
compounds and hence supported the formation of adenine from
CH
3
COONH
Therefore, through a series of experiments, formation of ade-
nine from CO , H O and NH in the gas phase and solution phase
is confirmed. Since the working of both gas phase and solution
4
.
2
2
3
1
3