1958
J. S. Yadav et al.
LETTER
O
O
a
b
O
OH
OBn
O
O
OH
OBn
OH OH
OBn
12
11
6
c, d
e, f
g
OBn
O
O
OBn
OTs OH
13
14
h
i, j
OH
15
OBn
OBn
O
OTES
O
16
4
Scheme 3 Reagents and conditions: (a) LiAlH4, 0–25 °C, 4 h, 85%; (b) 2,2-DMP, CSA (cat.), CH2Cl2, 25 °C, 1 h; (c) TsCl, Et3N, 0–25 °C,
CH2Cl2, 90%; (d) Me2CuLi, Et2O, 0–25 °C, 90%; (e) 2 N HCl, THF–H2O, 90%; (f) TsCl, Et3N, 0–25 °C, CH2Cl2, 85%; (g) LiAlH4, Et2O,
0–25 °C, 4 h, 90%; (h) IBX, DMSO–THF, 88%; (i) Pd/C, H2, EtOAc, 95%; (j) TESOTf, 2,6-lutidine, –78 °C, 92%.
a
ref. 6
O
O
OH
O
OTES
OTES
OH
O
OTBS
4
2
(–)-maurenone (1)
Scheme 4 Reagents and conditions: (a) LiHMDS, Et2O, –78 °C to –50 °C, then 3, –78 °C, 55%.
The synthesis of fragment 4 began with bicyclic lactone 6. In conclusion, the formal synthesis of (–)-maurenone has
Benzyl and p-methoxybenzyl ethers of lactone 6 have been achieved in a stereocontrolled manner by silyl
been reported earlier by our group for the synthesis of triflate mediated opening of epoxy alcohol and desym-
fragments of rifamycin,9 discodermolide,10 scytoficin,11 metrization of the meso-bicyclic dihydrofuran using an
as well as the total synthesis of prelactone B,12 mem- asymmetric hydroboration. This synthetic sequence
brenone C,13 and crocacin C.14
provides an easy access to the construction of the key
fragment of maurenone.
The synthesis of fragment 4 was accomplished from com-
pound 11 which was prepared by our earlier method
(Scheme 3).15 1,3-Diol of compound 11 was protected as
its acetonide 12 with 2,2-DMP/CSA(cat.). The primary
hydroxyl group of 12 was tosylated with TsCl/Et3N and
then treated with dimethyllithiumcuprate to afford the
compound 13 in 90% yield. Deprotection of acetonide 13
gave the 1,3-diol, which was further converted into mono-
tosylated compound 14 in 85% yield. Reduction of 14
with LAH gave the secondary alcohol 15, which was then
subjected to IBX oxidation to furnish 16 in good yield.
Hydrogenolysis of benzyl ether 16 followed by TES pro-
tection with TESOTf afforded the known fragment 4 in
92% yield.
Acknowledgment
K.R. thanks the CSIR for the award of a fellowship.
References and Notes
(1) Manker, D. C.; Faulkner, D. J.; Xe, C. F.; Clardy, J. J. Org.
Chem. 1986, 51, 814.
(2) Davies-Colman, M. T.; Garson, M. J. Nat. Prod. Rep. 1998,
15, 477.
(3) Roll, D. M.; Biskupiak, J. E.; Mayne, C. L.; Ireland, C. M.
J. Am. Chem. Soc. 1986, 108, 6680.
(4) Hochlowski, J. E.; Faulkner, D. J.; Matsumoto, G. K.;
Clardy, J. J. Am. Chem. Soc. 1983, 105, 74.
The spectral data and optical rotations of 3 (Scheme 4)
and 4 were identical with the reported values. The
coupling of compounds 3 and 4 gave the key fragment 2
as diastereomeric mixtures which was consistent with
literature.6
(5) (a) Garson, M. J.; Goodman, J. M.; Paterson, I. Tetrahedron
Lett. 1994, 35, 6929. (b) Garson, M. J. Chem. Rev. 1993, 93,
1699. (c) Manker, D. C.; Garson, M. J.; Faulkner, D. J. J.
Chem. Soc., Chem. Commun. 1988, 1061. (d) Garson, M. J.;
Jones, D. D.; Small, C. J.; Liang, J.; Clardy, J. Tetrahedron
Lett. 1994, 35, 6921.
(6) Crossman, J. S.; Perkins, M. V. J. Org. Chem. 2006, 71, 117.
Synlett 2007, No. 12, 1957–1959 © Thieme Stuttgart · New York