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

Experimental for chapter 2
3H, OMe Min ), 3.65 (s, 3H, OMe Maj ), 2.90-2.85 (m, 1H, H b ), 2.76 (ddd, 1H, J 17.0, 9.0,
2.0, H cax ), 2.35 (d, 1H, J 17.0, H ceq ), 2.07 (p, 1H, J 7.5, CHMe 2Maj ), 1.28 (d, 6H, J 7.0,
CHMe 2Min ), 0.99 (d, 3H, J 7.5, CHMe 2Maj ), 0.92 (d, 3H, J 7.5, CHMe 2Maj ).
Synthesis of (4R,5R)- 2-((1S,6S)-6-isopropyl-5-methoxy-1-methylcyclohexa-2,4-
dienyl)-4,5-diphenyloxazoline (102c)
Ph
O
N
Ph
i) i-PrLi (1.5 eq.), DMPU (6eq)
-78 °C, 20 min
ii) MeI
Ph
6
O
1
N
Ph
2
Ph
6
O
1
N
Ph
2
Me
OMe
5
4
3
OMe
5
4
102c 103c
3
OMe
General procedure 4 was used employing oxazoline 101c (122 mg, 0.37 mmol) i-PrLi
(0.55 mmol in pentanes), DMPU (0.27 cm 3 , 6 eq) and methyl iodide (0.1 cm 3 ) quench
after 10 min. Flash chromatography (99:1 to 95:1 petrol:EtOAc) yielded oxazoline
102c (77 mg, 54%) as colourless flowers, 103c (11 mg, 9%) as a colourless oil, and
starting material (24 mg, 20%).
102c R f : 0.55 (4:1 petrol:EtOAc); Mpt: 135-7 °C (PhMe); [α] 19 D : –105 (c = 0.25,
CH 2 Cl 2 ); MS m/z (CI+): 388 (100%, MH + ); HRMS (ESI+) m/z found 388.2281 (MH
calcd. 388.2271); Microanalysis: % found (% calc’d for C 26 H 29 NO 2 ) C, 78.36 (80.59),
H, 7.45 (7.54), N 3.37 (3.61); IR ν max (film)/cm -1 : 2961 (m), 1659 (C=N), 1590, 1453,
1269, 1209, 1083; 1 H NMR: (CDCl 3 , 300 MHz) δ 7.47-7.21 (m, 10H, Ph), 6.04 (d,
1H, J 9.5, H6), 5.85 (dd, 1H, J 9.5, 6.0, H5), 5.23 (d, 1H, J 8.5, CHOPh), 5.13-5.06
(m, 2H, H4, CHNPh), 3.63 (s, 3H, OMe), 2.38 (d, 1H, J 3.0, H2), 2.08 (pd, 1H, J 7.0,
3.0, CHMe 2 ), 1.56 (s, 3H, Me), 1.10 (d, 3H, J 7.0, CHMe A Me B ), 1.10 (d, 3H, J 7.0,
CHMe A Me B ); 13 C NMR: (CDCl 3 , 75 MHz) δ 171.3 (C=N), 157.2 (C3), 141.9 (ipso-
Ph), 140.4 (ipso-Ph), 128.8 (Ph), 128.7 (Ph), 128.2 (para-Ph), 127.5 (para-Ph), 126.6
(Ph), 125.6 (Ph), 125.0 (C6), 122.0 (C5), 93.0 (C4), 88.8 (CHO), 78.7 (CHN), 54.2
(OMe), 51.4 (C2), 43.6 (C1), 30.7 (CHMe 2 ) , 25.0 (Me), 23.6 (CHMe A Me B ), 17.9
(CHMe A Me B ).
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