Abstract
A new procedure for the synthesis of β-hydroxy enones from
allenyl carbinols and aldehydes is described. The use of InCl3 to
promote reaction results in a mild and convenient protocol for the preparation
of β-hydroxy enones.
Key words
aldehydes - allenes - coupling - enones - indium
References
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General Procedure: To
a solution of indium(III)chloride (1.1 equiv) and benzaldehyde (1.5
equiv) in CH2 Cl2 was added drop-wise octa-1,2-dien-4-ol
(1 equiv) in CH2 Cl2 at 20 °C.
After stirring for 5 h at 20 °C, aq NaHCO3 was
added to the reaction mixture. The aqueous layer was extracted with
Et2 O (2×). After drying the combined organic
solution over anhyd Na2 SO4 , the solvents were
removed under reduced pressure. Fresh column chromatography (SiO2 ,
10% EtOAc in hexanes) afforded 3a in
73% yield. IR(neat): ν = 3444, 2922,
1628 cm-1 . 1 H NMR
(500 MHz, CDCl3 ): δ = 0.91 (t, 3 H, J = 7.3 Hz),
1.34 (m, 2 H), 1.44 (m, 2 H), 2.23 (m, 2 H), 2.96 (d, 2 H, J = 6.2 Hz),
3.55 (d, 1 H, J = 3.1
Hz), 5.20 (m, 1 H), 6.11 (dt, 1 H, J = 1.7,
16.0 Hz), 6.87 (dt, 1 H, J = 7.0,
16.0 Hz), 7.32 (m, 5 H). 13 C NMR (125
MHz, CDCl3 ): δ = 200.7, 149.7, 143.2,
130.8, 128.7, 127.8, 125.9, 70.3, 48.4, 32.5, 30.3, 22.5, 14.0.
HRMS calcd for C15 H20 O2 : 232.1463.
Found: 232.1460.
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