746
Braddock, Brown:
9.4, 6.6, 4α-H); 1.81 (1 H, dddd, J = 13.6, 9.4, 9.4, 5.5, 3β-H); 1.72 (3 H, br s, 7-H); 1.61 (1 H,
dddd, J = 13.6, 10.1, 6.6, 3.6, 3α-H); 0.99 (3 H, d, J = 6.8, 8-H); 0.98 (3 H, d, J = 6.8, 10-H).
13C NMR (50.3 MHz, CDCl3): 206.1 (C1), 145.3 (C5), 110.7 (C6), 57.5 (C2), 35.5 (C4), 28.2
(C9), 23.6 (C3), 22.2 (C7), 20.1 (C8), 19.5 (C10). MS (CI+, NH3), m/z (rel.%): 172 (M + 18+,
23), 155 (M + 1+, 10), 137 (100), 121 (15), 111 (23), 93 (18), 81 (33), 69 (31).
(±)-2-Isopropyl-5-m eth ylh ex-5-en -1-ol (12)
Sodium boroh ydride (27 m g, 0.6 m m ol) was added in on e portion to
a solution of
(±)-2-isopropyl-2-m eth ylh ex-5-en al (1) (77 m g, 0.5 m m ol) in eth an ol (10 m l). Water (10 m l)
was added after 10 m in followed by careful addition of dilute 1 M HCl (10 m l). Th e organ ics
were extracted with dieth yl eth er (3 × 10 m l), th e extracts com bin ed, dried (an h ydrous
MgSO4), filtered an d th e solven t evaporated to give th e title com poun d as a colourless oil
(78 m g, 100%). IR (th in film ): 3 600–3 100 br s (OH), 3 074 w (sp2 CH), 2 959 s (sp3 CH),
2 943 s (sp3 CH), 2 874 s (sp3 CH), 1 650 m (C=C), 1 454 m (sp3 CH def.), 1 387 m , 1 370 m ,
1 037 m , 886 m . 1H NMR (500 MHz, CDCl3): 4.72 (1 H, br s, 6-H); 4.70 (1 H, br s, 6-H); 3.61
(2 H, m , H-1), 2.09 (1 H, ddd, J = 14.7, 10.9, 5.9, 4α-H); 2.03 (1 H, ddd, J = 14.7, 9.3, 6.1,
4β-H); 1.83 (1 H, dqq, J = 6.9, 6.9, 4.7, 9-H); 1.74 (3 H, br s, 7-H); 1.50 (1 H, dddd, J = 13.8,
10.9, 6.1, 5.0, 4α-H); 1.40 (1 H, dddd, J = 3.8, 9.3, 7.8, 5.9, 4β-H); 1.34 (1 H, ddddd, J = 7.8,
5.0, 5.0, 5.0, 4.7, 2-H); 0.92 (3 H, d, J = 6.9, 8-H); 0.91 (3 H, d, J = 6.9, 10-H). 13C NMR (50.3 MHz,
CDCl3): 146.5 (C5), 110.0 (C6), 63.4 (C1), 46.0 (C2), 35.8 (C4), 27.7 (C9), 25.6 (C3), 22.3
(C7), 19.6 (C8), 19.0 (C10). MS (CI+, NH3), m/z (rel.%): 174 (M + 18+, 7), 157 (M + 1+, 100),
138 (13), 123 (47), 109 (10), 95 (83), 82 (94), 69 (67), 55 (38).
Effect of a Substoich iom etric Am oun t of Dim eth ylalum in ium Ch loride
on (±)-2-Isopropyl-2-m eth ylh ex-5-en al (1)
A solution of dim eth ylalum in ium ch loride in h exan e (0.2 m l, 1 m ol l–1, 20 m ole %) was
added to a stirred solution of (±)-2-isopropyl-2-m eth ylh ex-5-en al (1) (154 m g, 1 m m ol) in
dich lorom eth an e (2 m l) at room tem perature un der argon . Th e colourless solution was
stirred for 16 h an d th en quen ch ed with 1 M sulfuric acid (2 m l). Th e organ ics were ex-
tracted with dich lorom eth an e (3 × 10 m l), com bin ed, dried (an h ydrous MgSO4), filtered an d
th e solven t evaporated to give a pale yellow oil (148 m g). Th e crude m aterial was an alysed
by 1H NMR an d was foun d to con sist of a 1 : 2 : 2 m ixture of un reacted aldeh yde 1, iden tical
with previously prepared m aterial, (±)-2-isopropyl-5-m eth ylh ex-5-en -1-ol (12) an d
(±)-6-isopropyl-3-m eth ylcycloh ex-2-en -1-on e (13) (piperiton e)17 1H NMR (300 MHz, CDCl3):
.
5.83 (1 H, s, 6-H); 2.2–1.2 (6 H, m , 2-H, 3-H, 4-H, 8-H); 1.90 (3 H, s, 7-H); 0.95 (3 H, d, J =
6.7, 9-H); 0.93 (3 H, d, J = 6.7, 10-H).
Effect of th e Alkoxides 14a an d 14c Gen erated Directly from Two Equivalen ts
of (1R*,2R*)-(2) an d (1S*,2R*)-(2-Isopropyl-5-m eth yliden e)cycloh exan -1-ol (3)
on (±)-2-Isopropyl-2-m eth ylh ex-5-en al (1)
A solution of dim eth ylalum in ium in h exan e (0.2 m l, 1 m ol l–1, 0.2 m m ol) was added sepa-
rately to stirred solution s of (1R*,2R*)- an d (1S*,2R*)-(2-isopropyl-5-m eth yliden e)-
cycloh exan -1-ol (2) an d (3) (62 m g, 0.4 m m ol) in dich lorom eth an e (2 m l) at room tem pera-
ture un der argon . Vigorous effervescen ce occurred an d after
1
h
(±)-2-isopropyl-
2-m eth ylh ex-5-en al (1) (154 m g, 1.0 m m ol) was added to th e colourless solution s. After 16 h
Collect. Czech. Chem. Commun. (Vol. 65) (2000)