P. Ciuffreda et al. / Tetrahedron Letters 44 (2003) 3663–3665
3665
(E)-2-butene-1,4-diol (3a) was prepared by reduction of
diethyl fumarate, according to: Corlay, H.; Motherwell,
W. B.; Pennell, A. M. K.; Shipman, M.; Slawin, A. M.
Z.; Williams, D. J.; Binger, P.; Stepp, M. Tetrahedron
1996, 13, 4883–4902.
CHH), and 0.59 (1H, ddd, J=4.9, 4.9 and 8.4 Hz, cyPr
CHH).
15. Ferraboschi, P.; Grisenti, P.; Manzocchi, A.; Santaniello,
E. Tetrahedron: Asymmetry 1994, 5, 691–698.
16. Diols 5a and 6a were prepared by lithium aluminum
hydride reduction of the corresponding diethyl esters.
Diol 7a was prepared by DIBAL reduction of dimethyl
itaconate as described in Ref. 15. Assignment of the
structure of each regioisomer of produced monoben-
zoates was achieved by 1H NMR analysis (500 MHz) and
the most significant signals are as follows. 5b: (CDCl3) l
4.44–4.33 (2H, m, CH2OBz), 3.57–3.51 (2H, m, part AB
of system ABX, CH2OH), 1.00 (3H, d, J=7.0 Hz, CH3).
5c: (CDCl3) l 4.22 (1H, dd, J=5.6 and 10.5 Hz,
CHHOBz), 4.16 (1H, dd, J=6.3 and 10.5 Hz,
CHHOBz), 3.80–3.70 (2H, m, CH2OH), 1.06 (3H, d,
J=7.0 Hz, CH3). 6b: (CDCl3) l 4.29 (2H, t, J=7.0 Hz,
CH2OBz), 3.50 (1H, dd, J=5.6 and 10.5 Hz, CHHOH),
3.46 (1H, dd, J=6.3 and 10.5 Hz, CHHOH), 0.94 (3H, d,
J=7.0 Hz, CH3). 6c: (CDCl3) l 4.19 (1H, dd, J=5.6 and
10.5 Hz, CHHOBz), 4.13 (1H, dd, J=6.3 and 10.5 Hz,
CHHOBz), 3.64 (2H, t, J=6.3 Hz, CH2OH), 1.01 (3H, d,
J=7.0 Hz, CH3). 7c: (CDCl3) l 5.24 (1H, bs, ꢀCHH),
5.09 (1H, bs, ꢀCHH), 4.79 (2H, s, CH2OBz), 3.81 (2H, t,
J=6.3 Hz, CH2OH), 2.42 (2H, t, J=6.3 Hz, CH2
CH2OH).
14. All new compounds gave spectroscopic data in agreement
with the assigned structures. A typical procedure for
MML-mediated benzoylation of 1,4-diols: lipase (100 mg)
was added to a solution of substrate 4a (1.0 mmol) and
VB (1.2 mmol) in t-BuOMe (10.0 ml). The mixture was
allowed to react at room temperature under magnetic
stirring and the progress of the reaction monitored by
TLC (hexane/ethyl acetate, 70:30; v/v) and GLC. After
1.5 h the reaction had reached 90% conversion and the
enzyme was filtered off and washed with MeOH, the
solvents were distilled under vacuum. After flash chro-
matography (hexane/ethyl acetate, 70:30; v/v) pure com-
pound 4b was obtained as a colorless oil (58% yield): Rf
0.25 (hexane/ethyl acetate, 70:30; v/v); 1H NMR (500
MHz, CDCl3) l 8.03 (2H, d, J=7.7, o-Ph H), 7.53 (1H,
dd, J=7.7 and 7.7 Hz, p-Ph H), 7.42 (2H, dd, J=7.7 and
7.7 Hz, m-Ph H), 4.21 (1H, dd, J=6.3 and 11.2 Hz,
CHHOBz), 4.16 (1H, dd, J=7.0 and 11.2 Hz,
CHHOBz), 3.53 (1H, dd, J=6.3 and 11.2 Hz, CHHOH),
3.46 (1H, dd, J=7.0 and 11.2 Hz, CHHOH), 1.18 (2H,
m, cyPr CH), 0.64 (1H, ddd, J=4.9, 4.9 and 8.4 Hz, cyPr