FULL PAPERS
Tin-Catalyzed Selective Reductive Hydroamination of Alkynes
Kumar, U. Sharma, P. K. Verma, N. Kumar, B. Singh,
Experimental Section
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All reagents and solvents were obtained from commercial
suppliers and were used without further purification for all
reaction. Column chromatography was carried out with 60–
120, 100–200 and 230–400 mesh silica gel and monitored
with TLC on silica gel 60 F254 plates using UV light as visu-
alizing agent. 1H and 13C NMR spectra were obtained on
300 MHz and 600 MHz instruments. Chemical shifts are re-
ported in ppm relative to CHCl3 downfield from an internal
standard. UV-Vis spectra were recorded on UV-Vis spectro-
photometer and Mass spectra were recorded on electrospray
ionization quadrupole time of flight (ESI-QTOF-MS) mass
spectrometer. The GC analysis was carried out on Gas
Chromatogram, an AOC-20i autosampler coupled, and BP
20 capillary column (30 m 0.25 mm i.d. 0.25 mm). The ini-
tial temperature of the column was held at 708C for 5 min
and was programmed to 2308C at 48CminÀ1, then held for
15 min at 2308C, the sample injection volume was 1 mL in
GC grade dichloromethane. Nitrogen was used as the carrier
gas at a flow rate of 1.1 mLminÀ1.
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General Procedure for Reductive Hydroamination of al-
kynes.
To an oven dried 15 mL test tube was added Sn(OTf)2
(0.1 mmol), aniline or N-alkylaniline (1.0 mmol), alkyne
(1.0 mmol), toluene (3 mL), EtOH (3.0 mmol) and PMHS
(4.0 mmol). The test tube was capped and the reaction mix-
ture was then heated to 1208C under air in an oil bath.
After completion of the reaction as observed by TLC, the
reaction mixture was allowed to cool, filtered and passed
through anhydrous sodium sulphate. The crude product was
purified by column chromatography over silica gel (60–120,
100–200 and 230–400 mesh) with n-hexane or n-heptane and
an appropriate mixture of n-hexane and ethyl acetate.
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Caution: tin(II) triflate causes severe skin burns and eye
damage. Wear protective gloves, protective clothing, eye
protection and face protection.
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Acknowledgements
The authors are grateful to Director of the institute, CSIR-
IHBT, for encouragement and support. M.S.T, M.K. and S.S
also thanks UGC for granting fellowships. Financial support
for this work was generously provided by CSIR-New Delhi
(in the form of 12th Five-Year Plan Program, ORIGIN, CSC-
0108).
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Adv. Synth. Catal. 2016, 358, 1103 – 1109
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