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

Experimental for chapter 2
Synthesis of (4R*,5R*)-2-(2-ethyl-4-methoxyphenyl)-4,5-diphenyloxazoline (120)
Ph
Ph
Ph
Ph
O
N
i) i-PrLi (3 eq.), DMPU (6 eq)
−78 °C
O
1
N
ii) MeI
6
2
OMe
5
4
OMe
3
General procedure 4 was used employing oxazoline 103b (250 mg, 0.73 mmol) i-PrLi
(2.19 mmol in pentane), DMPU (0.52 cm 3 , 6 eq) in THF to give a wine red solution,
and a methyl iodide (0.27 cm 3 ) quench after 5 min. Flash chromatography (19:1 to 9:1
petrol:EtOAc) yielded oxazoline 120 (170 mg, 65%) as a colourless oil.
R f : 0.39 (4:1, petrol:EtOAc); MS m/z (ES+) 358 (100%, MH + ), 359 (30%, (M+1)H + );
HRMS: found 358.1802, MH requires 358.1802; ¹H-NMR (CDCl 3 , 500 MHz) δ 7.89
(d, 1H, J 8.5, H6), 7.31-7.16 (m, 10H, Ph), 6.75 (d, 1H, J 2.5, H3), 6.67 (dd, 1H, J 8.5,
2.5, H5), 5.19 (d, 1H, J 7.5, CHOPh), 5.14 (d, 1H, J 7.5, CHNPh), 3.70 (s, 3H, OMe),
3.11-3.05 (m, 2H, CH 3 ), 1.18 (t, 3H, J 7.5, CH 2 Me); ¹³C-NMR (CDCl 3 , 125 MHz) δ
164.0 (C=N), 161.5 (C4), 147.6 (C2), 142.4 (ipso-Ph), 140.7 (ipso-Ph), 132.3 (C6),
128.8 (meta-Ph), 128.7 (meta-Ph), 128.2 (para-Ph), 127.5 (para-Ph), 126.5 (ortho-Ph),
125.6 (ortho-Ph), 115.3 (C3), 110.6 (C5), 87.8 (CHO), 79.2 (CHN), 55.1 (OMe), 27.8
(CH 2 ), 15.6 (Me).
210