A Route to Carbasugar Analogues - Jonathan Clayden - The ...

Experimental for chapter 3.1
Synthesis of (4R,5S)-2,4,5-triphenyloxazoline (109a) and (4R, 5S)-2-(4-
methoxyphenyl)-4,5-diphenyloxazoline (109b)
Ph Ph
O NH 2
O N
Ph Ph
O N
i) (Et 3 O)BF 4
109b
OMe
ii)
O NH 2
OMe
HO
Ph
H 2 N
Ph
109a
1
4
2
3
General procedure 3 was used mixing benzamide (89 mg, 0.74 mmol) para-anisamide
(112 mg, 0.74 mmol) with the triethyloxonium salt (265 mg, 1.39 mmol), stirring for
27 hr, before addition of the α-amino alcohol (350 mg, 1.5 mmol) and reflux for 24 hr.
Purification by flash chromatography (9:1 petrol:EtOAc), and recrystallisation from
toluene/hexane yielded oxazoline 109a (155 mg, 70%) as clear colourless flowers and
anisole 109b (160 mg, 66%) as colourless needles.
109a R f : 0.41 (4:1 petrol:EtOAc); Mpt: 134-135 °C (toluene); [α] 25 D : +159 (c = 0.2,
EtOH); MS m/z (CI+): 300 (100%, MH + ), 301 (20%, (M+1)H + ); HRMS (ESI+) m/z
found 300.1387 (MH calcd. 300.1383); IR ν max (film)/cm -1 : 1643 (C=N), 1451, 1269;
1 H-NMR (CDCl 3 , 500 MHz) δ 8.21 (d, 2H, J 7.0, ortho-Ph), 7.60 (tt, 1H, J 8.5, 2.0,
para-Ph), 7.55-7.51 (m, 2H, Ph), 7.11-7.02 (m, 6H, Ph), 7.00-6.95 (m, 4H, Ph), 6.0 (d,
1H, J 10.0, CHO), 5.79 (d, 1H, J 10.0, CHN); 13 C-NMR (CDCl 3 , 75 MHz) δ 164.9
(CNO), 137.7 (ipso-Ph), 136.6 (ipso-Ph), 131.8, 128.6, 128.6, 127.9, 127.7, 127.6,
127.5 (ipso-Ph), 127.4, 127.0, 126.3 (Ph), 85.3 (COPh), 74.5 (CNPh).
109b R f : 0.23 (4:1 petrol:EtOAc); Mpt: 126 °C (tolene/petrol); [α] 20 D : +162 (c = 0.45
EtOH); MS m/z (CI+): 330 (100%, MH + ), 331 (23%, (M+1)H + ); HRMS (ESI+) m/z
found 330.1492 (MH calcd. 330.1489); IR ν max (film)/cm -1 : 1644 (C=N), 1608, 1511,
1255; 1 H-NMR (MeOD, 300 MHz) δ 8.07 (d, 2H, J 9.0, H2), 7.12-6.92 (m, 12H, Ph),
6.12 (d, 1H, J 10.0, CHO), 5.75 (d, 1H, J 10.0, CHN), 3.90 (s, 3H, OMe); 13 C-NMR
(CDCl 3 , 125 MHz) δ 164.7 (CO), 162.5 (C4), 137.9 (ipso-Ph), 136.7 (ipso-Ph), 130.3,
127.9, 127.6, 127.6, 126.3, 127.3, 126.9, 119.9 (C1), 113.9, 85.1 (COPh), 74.3
(CNPh), 55.4 (OMe).
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