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4.3.1. General procedure for isolation of aryl azides 2a-j and recovery of TBSnN3
After the above-described procedure, 20 µL of o-DCB (internal standard) was added to the
reaction mixture followed by appropriate dilution with Et2O (to 50 mL) for quantitative GC MS
analysis. Thereafter, NaN3 (0.156 g, 2.4 mmol) was added to the MeCN Et2O resulting solution and
‒
‒
the suspension was left overnight under stirring at room temperature. The precipitated NaOTs was
filtered off under vacuum, rinsed with Et2O (3 × 5 mL) and the filtrate solution was washed
successively with distilled water (5 × 15 mL) and brine. The organic layer was dried over MgSO4,
filtered and concentrated under reduced pressure.
For aryl azides 2a-g, the residue obtained after complete removal of solvent, was subjected to
flash chromatography on silica gel pre-treated with Et3N (10% v/v) giving the corresponding
product in fractions eluted with hexanes. Then, after a fast increasing of eluting power, the TBSnN3
was recovered from AcOEt fractions in around 80 % yield.
Instead, the aryl azides 2h-j were precipitated from the concentrated filtrates by dropwise
addition of cold hexane, and pure products were obtained by recrystallization from the same
solvent. The TBSnN3 was then recovered from the supernatants, in near quantitative yield, after
solvent removal and vacuum drying.
Azidobenzene (2a). Following the general procedures within 2 hours of reaction, 77 % yield of
1
the title compound was obtained as yellow oil ; H NMR (300 MHz, CDCl3)
δ
7.50
‒
7.41, (m, 2H),
140.0,
+ ), 91 [100, (M+·‒ N2)], 64 (61).
1-Azido-2-chlorobenzene (2b). Following the general procedures within 2 hours of reaction, 68
% yield of the title compound was obtained as yellow oil; 1H NMR (300 MHz, CDCl3)
7.29 (dd, J
= 8.0, 1.5 Hz, 1H), 7.25–7.17 (td, J = 8.1, 1.5 Hz, 1H), 7.10 (dd, J = 8.0, 1.5 Hz, 1H), 7.00 (td, J =
7.7, 1.5 Hz, 1H); 13C NMR (75 MHz, CDCl3)
137.3, 130.9, 128.0, 125.8, 125.2, 119.8; MS m/z
(% rel. intensity, ion) 153 (22, M+ ), 125 [100, (M+
-N2)], 90 (69), 63 (48).
1-Azido-3-chlorobenzene (2c). Following the general procedures within 2 hours of reaction, 87
% yield of the title compound was obtained as pale yellow oil; 1H NMR (300 MHz, CDCl3)
7.20
(t, J = 8.0 Hz, 1H), 7.06 (ddd, J = 8.0, 1.9, 1.0 Hz, 1H), 7.03 (d, J = Hz, 1H), 6.96 (t, J = 2.1 Hz,
1H), 6.86 (ddd, J = 8.1, 2.2, 1.0 Hz, 1H); 13C NMR (75 MHz, CDCl3)
141.6, 135.6, 130.8, 125.2,
119.5, 117.4; MS m/z (% rel. intensity, ion) 153 (22, M+ ), 125 [100, (M+
- N2)], 90 (69), 63 (48).
7.26 (t, J = 7.4 Hz, 1H), 7.14 (dd, J = 8.6, 1.1 Hz, 2H); 13C NMR (75.5 MHz, CDCl3)
δ
129.7, 124.8, 119.0; MS m/z (% rel. intensity, ion) 119 (25, M
·
δ
δ
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δ
δ
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1-Azido-4-chlorobenzene (2d). Following the general procedures within 1 hour of reaction, 77 %
1
yield of the title compound was obtained as yellow oil; H NMR (300 MHz, CDCl3)
δ
7.20 (d, J =
138.8, 130.3, 129.9, 120.3; MS
- N2)], 90 (69), 63 (48).
8.7 Hz, 2H), 6.85 (d, J = 8.7 Hz, 2H); 13C NMR (75 MHz, CDCl3)
m/z (% rel. intensity, ion) 153 (22, M+ ), 125 [100, (M+
δ
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