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Helvetica Chimica Acta – Vol. 94 (2011)
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Data of (E)-32: H-NMR: 1.18 – 1.54 (m, 16 H); 2.00 – 2.15 (m, 4 H); 2.33 (br. t, J ¼ 7.6, 2 H); 2.52
(dt, J ¼ 7.6, 1.8, 2 H); 5.13 (br. t, J ¼ 7.7, 1 H); 9.76 (t, J ¼ 1.8, 1 H). 13C-NMR: 22.3 (t); 22.5 (t); 24.0 (t);
24.3 (t); 24.6 (t); 24.7 (t); 25.0 (2t); 25.9 (t); 27.2 (t); 28.4 (t); 42.3 (t); 126.9 (d); 137.1 (s); 202.9 (d). MS:
222 (14, Mþ), 204 (8), 135 (22), 109 (34), 83 (100).
Data of (Z)-32: 1H-NMR: 1.18 – 1.53 (m, 16 H); 2.02 – 2.10 (m, 4 H); 2.34 – 2.40 (m, 2 H); 2.45 – 2.51
(m, 2 H); 5.36 (br. t, J ¼ 7.6, 1 H); 9.78 (t, J ¼ 1.8, 1 H). 13C-NMR: 21.2 (t); 23.8 (t); 24.3 (t); 24.4 (t); 24.8
(t); 25.4 (t); 25.9 (t); 26.5 (t); 26.8 (t); 27.4 (t); 35.2 (t); 42.7 (t); 129.6 (d); 135.5 (s); 202.5 (d). MS: 222 (20,
Mþ), 204 (14), 135 (40), 83 (92), 67 (100).
4.9. Undec-4-enal (33; (E)/(Z) 3 :1) [14]. Yield 10%. Mixture not separated. Colorless oil.
Data of (E)-33: 1H-NMR: 0.88 (t, J ¼ 6.9, 3 H); 1.18 – 1.40 (m, 8 H); 1.92 – 2.03 (m, 2 H); 2.28 – 2.38
(m, 2 H); 2.46 – 2.52 (m, 2 H); 5.34 – 5.52 (m, 2 H); 9.76 (t, J ¼ 1.8, 1 H). 13C-NMR: 14.1 (q); 22.6 (t); 25.2
(t); 28.8 (t); 29.4 (t); 31.7 (t); 32.5 (t); 43.6 (t); 127.7 (d); 132.2 (d); 202.3 (d). MS: 168 (0.5, Mþ), 150 (11),
124 (25), 97 (30), 84 (100).
Data of (Z)-33: 1H-NMR: 0.88 (t, J ¼ 6.9, 3 H); 1.18 – 1.40 (m, 8 H); 2.01 – 2.08 (m, 2 H); 2.33 – 2.41
(m, 2 H); 2.46 – 2.52 (m, 2 H); 5.28 – 5.46 (m, 2 H); 9.77 (t, J ¼ 1.8, 1 H). 13C-NMR: 14.1 (q); 20.1 (t); 22.6
(t); 27.2 (t); 29.0 (t); 29.5 (t); 31.8 (t); 43.9 (t); 127.0 (d); 131.8 (d); 202.2 (d). MS: 168 (0.2, Mþ), 150 (3),
124 (22), 97 (23), 84 (100).
4.10. Dodec-4-enal (34; (E)/(Z) 2.3 :1) [15]. Yield 10%. Mixture not separated. Colorless oil.
Data of (E)-34: 1H-NMR: 0.88 (t, J ¼ 6.9, 3 H); 1.18 – 1.40 (m, 10 H); 1.92 – 2.02 (m, 2 H); 2.28 – 2.38
(m, 2 H); 2.45 – 2.54 (m, 2 H); 5.33 – 5.53 (m, 2 H); 9.76 (t, J ¼ 1.8, 1 H). 13C-NMR: 14.1 (q); 22.7 (t); 25.3
(t); 29.1 (t); 29.2 (t); 29.5 (t); 31.9 (t); 32.5 (t); 43.6 (t); 127.7 (d); 132.2 (d); 202.3 (d). MS: 182 (0, Mþ),
138 (10), 110 (10), 97 (20), 84 (100).
Data of (Z)-34: 1H-NMR: 0.88 (t, J ¼ 6.9, 3 H); 1.18 – 1.41 (m, 10 H); 1.99 – 2.09 (m, 2 H); 2.32 – 2.42
(m, 2 H); 2.44 – 2.53 (m, 2 H); 5.27 – 5.37 (m, 1 H); 5.38 – 5.48 (m, 1 H); 9.77 (t, J ¼ 1.8, 1 H). 13C-NMR:
14.1 (q); 20.1 (t); 22.7 (t); 27.3 (t); 29.2 (t); 29.3 (t); 29.6 (t); 31.9 (t); 43.9 (t); 127.1 (d); 131.8 (d); 202.2
(d). MS: 182 (0, Mþ), 138 (24), 110 (14), 97 (31), 84 (100).
4.11. 4-(Cyclopent-1-en-1-yl)butanal (¼Cyclopent-1-ene-1-butanal; 35). Yield 15%. Colorless oil.
1H-NMR: 1.75 – 1.90 (m, 4 H); 2.08 – 2.15 (m, 2 H); 2.18 – 2.25 (m, 2 H); 2.26 – 2.33 (m, 2 H); 2.43 (dt, J ¼
7.2, 1.8, 2 H); 5.34 – 5.38 (m, 1 H); 9.77 (t, J ¼ 1.8, 1 H). 13C-NMR: 20.2 (t); 23.4 (t); 30.4 (t); 32.4 (t); 34.9
(t); 43.5 (t); 124.4 (d); 143.5 (s); 202.7 (s). MS: 138 (1.6, Mþ), 120 (33), 94 (100), 79 (100), 67 (55).
4.12. 4-(Cyclohex-1-en-1-yl)butanal (¼Cyclohex-1-ene-1-butanal; 36). Yield 17%. Colorless oil. 1 H-
NMR: 1.49 – 1.66 (m, 4 H); 1.70 – 1.80 (m, 2 H); 1.86 – 1.94 (m, 2 H); 1.94 – 2.02 (m, 4 H); 2.42 (dt, J ¼ 7.3,
1.8, 2 H); 5.39 – 5.43 (m, 1 H); 9.78 (t, J ¼ 1.8, 1 H). 13C-NMR: 20.1 (t); 22.5 (t); 22.9 (t); 25.2 (t); 28.1 (t);
37.3 (t); 43.4 (t); 122.1 (d); 136.5 (s); 202.8 (d). MS: 152 (2.9, Mþ), 134 (64), 108 (63), 93 (75), 79 (100), 67
(48).
5. 8-(tert-Butyl)-2-oxo-1-oxaspiro[4.5]decane-3-carboxaldehyde (aldehyde-2; (5a,8b)/(5a,8a)
2.3 :1) and 8-(tert-butyl)-3-(hydroxymethylene)-1-oxaspiro[4.5]decan-2-one (enol-2; (E)/(Z) ca. 2 :1;
(5a,8b)/(5a,8a) 1:1) (aldehyde/enol ca. 2 :1). A mixture of 8-(tert-butyl)-1-oxaspiro[4.5]decan-2-one
(3) [4] (trans/cis 2.3 :1; 9.8 g, 47 mmol), HCOOEt (7 g, 94 mmol), and MeOK (5 g, 71 mmol) in tBuOMe
(300 ml) was mechanically stirred at 408 during 2 h under N2. The mixture was then cooled to r.t. and
poured into cold 10% aq. HCl soln. (200 ml). Extraction (Et2O), workup, and crystallization from
pentane afforded 2 (diastereoisomer mixtures of aldehyde and enol tautomers; 9.8 g, 88%). White
crystals. M.p. 123 – 1258. B.p. 1358/0.1 mbar. 1H-NMR: 0.84 – 0.90 (3s, 54 H); 0.97 – 1.23 (m, 14 H); 1.32 –
2.03 (m, 40 H); 2.08 (dd, J ¼ 10.1, 13.4, 1 H, aldehyde); 2.23 (dd, J ¼ 10.2, 13.4, 1 H, aldehyde); 2.40 – 2.51
(m, 2 H, aldehyde); 2.58 (br. d, J ¼ 1.9, 2 H, (Z)-enol); 2.60 (br. d, J ¼ 2.5, 2 H, (E)-enol); 2.66 (br. d, J ¼
1.9, 2 H, (Z)-enol); 2.68 (br. d, J ¼ 2.4, 2 H, (E)-enol); 3.74 – 3.82 (m, 2 H, aldehyde); 7.02 (br. s, 1 H, (Z)-
enol); 7.67 (br. s, 1 H, (E)-enol); 8.53 (br. s, 1 H, (E)-enol); 8.68 (br. s, 1 H, (E)-enol); 9.87 (s, 2 H,
aldehyde); 10.23 (br. s, 1 H, (Z)-enol). MS (major peak: 70%): 238 (7, Mþ), 220 (20), 119 (31), 94 (36),
57 (100). MS (minor peak: 30%): 238 (11, Mþ), 220 (32), 182 (77), 119 (81), 94 (100).
Data of (5a,8b)-Aldehyde-2: 13C-NMR: 29.6 (t); 54.2 (d); 87.3 (s); 171.2 (s); 194.7 (d).
Data of (5a,8a)-Aldehyde-2: 13C-NMR: 33.3 (t); 53.9 (d); 85.7 (s); 171.5 (s); 194.8 (d).
Data of (Z)-Enol-2: 13C-NMR: 86.3, 88.0 (2s); 100.9 (s), 101.0 (2s); 156.3, 156.4 (2d); 174.9, 175.1
(2s).