Synthesis of a-Hydroxy Ketones from Terpene Aldehydes
2597
3
3.82 (d, J ¼ 4.36, 1H, OH), 2.18 (s, 3H, C(3)–H3), 2.24–1.60 (m, 7H,
C(30)–H2, C(40)–H, C(50)–H2, C(60)–H2), 1.73 (s, 3H, C(9)–H3). 13C-
NMR d (100 MHz, CDCl3): 208.4 (C55O), 149.2 C(70), 109.0 C(80), 135.0
C(10), 129.4 C(20), 82.2 C(1), 41.22 C(40), 30.82 C(60), 27.18 C(50), 24.71
†
C(3), 23.16 C(30), 20.62 C(90). MS (EI, 70 eV): m/z 194 (Mþ , 3), 151
(100), 149 (46), 45 (10), 43 (72). IR n (film, cm21): 3447 (br), 1713. The
analytical data matched those of enantiomeric (S)-4b.
(1S)-1-Hydroxy-1-[(40R)-40-isopropenyl-1-cyclohexen-1-yl)-2-propa-
1
none, (S)-4a. H-NMR d (400 MHz, CDCl3): 5.95 (m, 1H, C(20)–H), 4.74
3
(m, 1H, C(10)–H), 4.68 (m, 1H, C(10)–H); 4.51 (d, J ¼ 4.45, 1H, C(1)–
3
H), 3.77 (d, J ¼ 4.36, 1H, OH), 2.15 (s, 3H, C(3)–H3), 2.24–1.60 (m, 7H,
C(30)–H2, C(40)–H, C(50)–H2, C(60)–H2), 1.73 (s, 3H, C(30)–H3). 13C-NMR
d (100 MHz, CDCl3) 208.6 C(2), 149.0 C(70), 108.9 C(80), 134.8 C(10), 128.8
C(20), 82.5 C(1), 40.14 C(40), 30.57 C(60), 26.98 C(50), 24.84 C(3), 23.08
†
C(30), 20.85 C(90). MS (EI, 70 eV): m/z 194 (Mþ , 3), 151 (100), 149 (40),
45 (12), 43 (90). IR n (film, cm21): 3460 (br), 1713. The analytical data
matched those of enantiomeric (R)-4b.
(1R,10R)-1-(6,6-Dimethyl-bicyclo[3.1.1]hept-2-en-2-yl)-1-hydroxy-2-pro-
1
panone, (1R)-4c. [a]D ¼ 2 2918 (CHCl3, c ¼ 0.520). H-NMR d (400 MHz,
CDCl3): 5.75 (s, 1H, C(30)–H), 4.53 (d, 3J ¼ 3.6, 1H, C(1)–H), 3.66
3
3
(d, J ¼ 4.2, 1H, OH), 2.42–2.37 (m, 1H, C(70)–H), 2.35 (t, J ¼ 2.9, 2H,
C(40), 2.16 (s, 3H, C(3)–H3), 2.14–2.09 (m, 1H, C(50)–H), 1.92 (td, J ¼ 5.5,
J ¼ 1.5, 1H, C(10)–H), 1.25 (s, 3H, C(60)–CH3), 1.05 (d, 2J ¼ 8.7, 1H, C(70)–
H), 0.85 (s, 3H, C(60)–CH3). 13C-NMR d (100 MHz, CDCl3): 208.1 (C55O),
144.5 C(20), 124.8 C(30), 80.7 C(1), 41.28 C(10), 40.78 C(50), 38.09 C(60),
32.11 C(70), 31.67 C(40), 25.96 C(90), 25.04 C(3), 21.06 C(80). MS (EI, 70 eV):
†
m/z 194 (Mþ , 0.5), 151 (13), 149 (2), 45 (10), 43 (100). IR n (film, cm21):
3474 (br), 1716.
(1S,10R)-1-(6,6-Dimethyl-bicyclo[3.1.1]hept-2-en-2-yl)-1-hydroxy-2-pro-
1
panone, (1S)-4c. [a]D ¼ þ 2978 (CHCl3, c ¼ 0.520). H-NMR d (400 MHz,
CDCl3): 5.75 (s, 1H, C(30)–H), 4.60 (d, 3J ¼ 3.2, 1H, C(1)–H), 3.75
3
2
(d, J ¼ 4.56, 1H, OH), 2.49–2.43 (m, 1H, C(70)–H), 2.35 (dt, J ¼ 18.2,
3J ¼ 2.46, 2H, C(40), 2.18 (s, 3H, C(3)–H3), 2.15–2.10 (m, 1H, C(50)–H),
2.14–2.06 (m, J ¼ 1.5, 1H, C(10)–H), 1.28 (s, 3H, C(60)–CH3), 1.22
2
(d, J ¼ 8.76, 1H, C(70)–H), 0.82 (s, 3H, C(60)–CH3). 13C-NMR d (100 MHz,
CDCl3): 207.4 (C55O); 144.6 C(20), 124.3 C(30), 81.0 C(1), 41.66 C(10), 40.51
C(50), 37.54 C(60), 32.01 C(70), 31.47 C(40), 26.01 C(90), 25.34 C(3), 21.35
†
C(80). MS (EI, 70 eV): m/z 194 (Mþ , 0.5), 151 (13), 149 (2), 45 (10), 43
(100). IR n (film, cm21): 3456 (br), 1716.
(Z)-3-Hydroxy-5,9-dimethyl-deca-4,8-dien-2-one, (R,S)-4d. A commer-
cially available mixture of neral and geranial was used as starting material in the
synthesis, and the E- and Z-isomers 4d and 4e were then separated by flash