D
Synlett
K. Wada et al.
Letter
85% yield (Scheme 5). TMS ether 6a was directly subjected
Acknowledgment
to lactonization with p-TsOH·H O, furnishing 1 in 82%
2
This study was supported by a Grant-in-Aid for Scientific Research
from the Ministry of Education, Culture, Sports, Science, and Technol-
ogy, Japan (26410111).
16
yield. On the other hand, the substitution of (Z)-5b was
slow at temperatures between –40 °C to –5 °C and contin-
ued at room temperature overnight, affording a mixture of
6
b (87% ds) and unidentified product(s) after the hydrolysis
Supporting Information
of the TMS ether.
The reactivity and diastereoselectivity being different
between the olefin isomers might be explained using con-
formers A and B for the E- and Z-isomers, respectively
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0035-1561576.
S
u
p
p
ortioIgnfmr oaitn
S
u
p
p
o
nrtogI
i
f
rm oaitn
(
Scheme 6). Conformer A constitutes a stable conformer be-
References and Notes
cause of no severe steric obstacles, thus allowing a normal
access of the methyl copper reagent from the equatorial di-
rection. In contrast, conformer B might exist in equilibrium
with other conformer(s) such as a pseudo-skewed boat con-
former C to release steric repulsion between the two side
chains in conformer B. The axial hydrogen H overhanging
(1) (a) Rocca, J. R.; Nation, J. L.; Strekowski, L.; Battiste, M. A. J. Chem.
Ecol. 1992, 18, 223. (b) Lu, F.; Teal, P. E. A. Arch. Insect Biochem.
Physiol. 2001, 48, 144. (c) Teal, P. E. A.; Meredith, J. A.; Gomez-
Simuta, Y. Arch. Insect Biochem. Physiol. 1999, 42, 225. (d) Baker,
J. D.; Heath, R. R. J. Chem. Ecol. 1993, 19, 1511. (e) Robacker, D. C.
J. Chem. Ecol. 1988, 14, 1715. (f) Stokes, J. B.; Uebel, E. C.;
Warthen, J. D.; Jacobson, M. Jr.; Flippen-Anderson, J. L.; Gilardi,
R.; Spishakoff, L. M.; Wilzer, K. R. J. Agric. Food Chem. 1983, 31,
17
e
on the allylic olefin is probably the reason for the slower re-
action of (Z)-5b.
1162. (g) Walse, S. S.; Alborn, H. T.; Teal, P. E. A. Green Chem.
Hb
Hd
Lett. Rev. 2008, 1, 205. (h) Strekowski, L.; Visnick, M.; Battiste,
M. A. J. Org. Chem. 1986, 51, 4836.
Hc
RO
major
(
2) Battiste, M. A.; Strekowski, L.; Vanderbilt, D. P.; Visnick, M.;
(
E)-5b
6
Me
t-BuO2C
Ha
OCO(2-Py)
King, R. W. Tetrahedron Lett. 1983, 24, 2611.
99% ds
minor
(3) (a) Mori, K.; Nakazono, Y. Liebigs Ann. Chem. 1988, 167.
(b) Tadano, K.; Isshiki, Y.; Minami, M.; Ogawa, S. J. Org. Chem.
faster reaction
higher ds
conformer A
1993, 58, 6266. (c) Irie, O.; Shishido, K. Chem. Lett. 1995, 53.
(
4) (a) Battiste, M. A.; Strekowski, L.; Coxon, J. M.; Wydra, R. L.;
Harden, D. B. Tetrahedron Lett. 1991, 32, 5303. (b) Saito, A.;
Matsushita, H.; Kaneko, H. Chem. Lett. 1984, 729. (c) Battiste, M.
A.; Strekowski, L.; Vanderbilt, D. P.; Visnick, M.; King, R. W. Tet-
rahedron Lett. 1983, 24, 2611.
RO
Me
t-BuO2C
conformer B
OCO(2-Py)
(
5) Kaneko, Y.; Kiyotsuka, Y.; Acharya, H. P.; Kobayashi, Y. Chem.
Commun. 2010, 46, 5482.
He
Hf
RO
(
Z)-5b
6
(6) (a) Feng, C.; Kobayashi, Y. J. Org. Chem. 2013, 78, 3755. (b) Feng,
C.; Kaneko, Y.; Kobayashi, Y. Tetrahedron Lett. 2013, 54, 4629.
Hb
8
3% ds
Hd
Me
Ha
(c) Ozaki, T.; Kobayashi, Y. Org. Chem. Front. 2015, 2, 328.
Hc
slower reaction
lower ds
(d) Ozaki, T.; Kobayashi, Y. Synlett 2015, 26, 1085. (e) Kiyotsuka,
Y.; Kobayashi, Y. J. Org. Chem. 2009, 74, 7489. (f) Kiyotsuka, Y.;
Katayama, Y.; Acharya, H. P.; Hyodo, T.; Kobayashi, Y. J. Org.
Chem. 2009, 74, 1939. (g) Kiyotsuka, Y.; Acharya, H. P.;
Katayama, Y.; Hyodo, T.; Kobayashi, Y. Org. Lett. 2008, 10, 1719.
7) (a) Kawashima, H.; Kaneko, Y.; Sakai, M.; Kobayashi, Y. Chem.
Eur. J. 2014, 20, 272. (b) Kawashima, H.; Sakai, M.; Kaneko, Y.;
Kobayashi, Y. Tetrahedron 2015, 71, 2387.
t-BuO2C
OCO(2-Py)
skewed-boat conformer C
other conformers
(
(
Scheme 6 Plausible conformers in the substitution of (E)-5b and (Z)-
b with the methyl copper reagent
5
8) Ozaki, T.; Kobayashi, Y. Synlett 2015, 26, 1085.
In summary, we have developed a stereoselective syn-
(9) Visnick, M.; Strekowski, L.; Battiste, M. A. Synthesis 1983, 284.
10) (a) Belmont, D. T.; Paquette, L. A. J. Org. Chem. 1985, 50, 4102.
(
(
(
thesis of anastrephin (1) from commercially available
ethoxy enone 7 through allylic substitution of picolinate 5b
consisting of an (E)- and (Z)-olefin stereoisomers in 5.5%
(b) Jyothi, D.; HariPrasad, S. Synlett 2009, 2309.
11) Hansson, M.; Arvidsson, P. I.; Lill, S. O. N.; Ahlberg, P. J. Chem.
Soc., Perkin Trans. 2 2002, 763.
12) Holub, N.; Neidhöfer, J.; Blechert, S. Org. Lett. 2005, 7, 1227.
yield over 15 steps with 91% ds. These results are higher
than those reported for the previous syntheses of 1.1
8,19
Fur-
(13) Wu, K.-M.; Okamura, W. H. J. Org. Chem. 1990, 55, 4025.
thermore, we clarified that the E isomer of 5b gave higher
diastereoselectivity than the Z isomer (99% ds vs. 85% ds).
The present method would spur on biological study of
anastrephin.
(14) Enantiomeric purity of 13 was calculated to be 95% ee based on
99% ee of 10 and 98% ds of 12.
(
(
15) Strekowski, L.; Visnick, M.; Battiste, M. A. Synthesis 1983, 493.
16) Anastrephin (1) prepared from (E)-5 (95% ee): [α]D21 –39 (c
26
0
.37, hexane) and mp 91.5–93.0 °C. Compare ref. 3b [α] –45.1
D
23 5
(
c 0.51, hexane) and mp 88.0–89.5 °C; ref. 3a [α]D . –50.4 (c
©
Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–E