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

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Experimental for chapter 4.2<br />

Synthesis of (1R,2R,5S,6S)-5-(hydroxymethyl)-6-isopropyl-5-methylcyclohex-3-<br />

ene-1,2-diol (312)<br />

Ph<br />

Ph<br />

O<br />

NMe<br />

i) H 3 O + , 50 °C<br />

HO<br />

6<br />

1<br />

2<br />

OH<br />

OH<br />

ii) NaBH 4<br />

5<br />

4<br />

OH<br />

3<br />

OH<br />

General procedure 7 was employed using oxazolidine 310 (50 mg, 0.12 mmol), and the<br />

reaction heated at 50 °C for 24 hr. Flash chroma<strong>to</strong>graphy (3:2 petrol:EtOAc) yielded<br />

triol 312 (19 mg, 79%) as colourless needles.<br />

R f : 0.34 (EtOAc); Mpt: 136-138 ºC (MeOH); [α] 22 D : +10.8 (c = 1.7, MeOH); MS m/z<br />

(ES+) 223 (100%, MNa + ), 224 (15%, (M+1)Na + ); HRMS: found 223.1299, MNa<br />

requires 223.1305; IR ν max (film)/cm⎯¹ 3348 (br, O-H), 2958 (m, C-H), 1651 (w, C=C);<br />

¹H-NMR (CD 3 OD, 500 MHz) δ 5.60 (dd, 1H, J 10.0, 1.5, H5), 5.44 (dd, 1H, J 10.0,<br />

2.0, H6), 4.00 (d, 1H, J 7.5, H4), 3.91 (dd, 1H, J 12.0, 7.5, H3), 3.59 (d, 1H, J 11.0,<br />

H7), 3.39 (d, 1H, J 11.0, H7’), 2.03 (p, 1H, J 7.0, CHMe 2 ), 1.48 (d, 1H, J 12.0, H2),<br />

1.19 (d, 6H, J 7.0, i-Pr), 1.01 (s, 3H, Me); ¹³C-NMR (CD 3 OD, 75.5 MHz) δ 136.8<br />

(C5), 129.3 (C6), 76.3 (C4), 74.1 (C3), 67.7 (C7), 53.7 (C2), 44.9 (C1), 27.5 (CHMe 2 ),<br />

27.5 (CHMe A Me B ), 24.7 (Me), 18.1 (CHMe A Me B ).<br />

For dihydroxylation of 312 <strong>to</strong> give altrose analogue 278, see page 260<br />

Synthesis of (1S,4R,5R,6S)-5-hydroxy-6-isopropyl-1-methylcyclohex-2-ene-δlac<strong>to</strong>ne<br />

(328)<br />

Ph<br />

Ph<br />

O<br />

N<br />

Me<br />

MeOTf, then NH 4 Cl<br />

O<br />

1<br />

2<br />

OH<br />

O<br />

4<br />

3<br />

OH<br />

OH<br />

General procedure 6 was used employing oxazoline 213 (45 mg, 0.11 mmol) and<br />

methyl triflate (27 µl, 0.23 mmol) for 16 hr and an ammonium chloride (sat. aq., 0.5<br />

269

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