unsaturation. The 13C NMR and DEPT 90° and 135°
spectraresolved31carbon signalscomprising 9 quaternary
carbons, including 1 carbonyl, 7 methine carbons, 13
methylene carbons, and 2 methyl carbons.
The gross structure of 2 was elucidatedby analyses of 1D
and 2D NMR spectra (Table 1, Figure 1). The 13C NMR
shifts and DEPT 135° of C-2, C-3, C-4, C-5, C-10, and
C-11 revealed the presence of three acetylene groups. The
1
1Hꢀ H COSY spectra of 2 showed five partial structural
units. The HMBC correlation for H-12 to C-11 and C-10
and their 13C NMR shifts indicated the connection for
C-12 and C-11 and C-11 and C-10. The HMBC correlation
for H-8 to C-10, H-8 to C-9 and the 13C NMR shift of C-9
indicated a connection of C-10 and C-8 through C-9 which
is attached to sulfur. The HMBC correlation for H-8 to
C-7 indicated the connection of C-8 to C-7. This connec-
tion was supported by the J (H-8/H-7) value and corre-
sponding COSY correlation. The HMBC correlations for
H-7 to C-5, H-1 to C7, H-1 to C-6, and H-1 to C-5 and the
13C NMR shift of C-6 indicated the connection for C-7 and
C-5 through C-6 which is attached to S. The HMBC
correlation for H-1 to C-4, H-1 to C-3, and H-1 to C-2
and their 13C NMR shifts indicated the connections for
C-5 and C-4, C-4 and C-3, C-3 and C-2, and C-2 and C-1.
The 1H NMR shift of H-12 and 13C NMR shifts of C-12
suggested that C-12 was connected to a hydroxy group.
The HMBC correlation for H-13 to C-14 and the 1H NMR
shift of H-13 and 13C NMR shifts of C-13 indicated the
connection for C-13 and C-14 thorough an oxygen atom.
The HMBC correlation for H-15 to C-14 indicated the
connection for C-14 and C-15. The HMBC correlation for
H-21 to C-23, H-24 to C-22, H-24 to C-26, and H-27 to
C-25 suggested the connections for C-22 to C-23 and C-25
to C-26. The HMBC correlation for H-31 to C-29 and
H-31 to C-30 and their 13C NMR shifts suggested the
connection for C-29 to C-31 through C-30. The remaining
structural details were elucidated on the basis of 13C NMR
data of authentic linoleic acid data as well as GC-MS
spectrometry fragmentation data.8,9
Figure 1. Selected 2D NMR correlations for echinopsacetylenes
A (1) and B (2).
correlations are observed in this partial structure of poly-
acetylene thiophenes.6 The HMBC correlation for H-1 to
C-4, H-1 to C-3, and H-1 to C-2 and their 13C NMR shifts
indicated the connections for C-5 and C-4, C-4 and C-3,
C-3 and C-2, and C-2 and C-1. The 1H NMR shift of H-13
and 13C NMR shifts of C-13 suggested that C-13 was
connected to a hydroxy group. The HMBC correlation of
H-12 to C-14, H-12 to C-15, and H-15 to C-14 and the 13
C
NMR shift of C-14 indicated the connection for C-12 and
C-15through the quaternary olefinic C-14. The J (H-15/H-
16) value suggested theconnections for C-15and C-16. The
J (H-19/H-20) value suggested the connections for C-19
and C-20. The HMBC correlations for H-23 to C-22, H-23
to C-24, and H-25 to C-24 indicated the connection for
C-22 to C-25 through C-23 and C-24. These connections
were supported by the J (H-23/H-24) and J (H-24/H-25)
values. The remaining structural details were elucidated on
the basis of 13C NMR data of isolated R-terthienyl (3)
(Figure 2) data.5,7 Thus, the structure of echinopsacetylene
A was elucidated to be 1. The absolute configuration of 1
was not determined due to the limited quantity.
Moreover, to confirm the structure of 2, the GC-FID
and GC-MS analyses of methanolysates of 2 by treatment
(7) R-Terthienyl (3): 13C NMR data (150 MHz, CDCl3) δC: 137.1,
137.1, 136.2, 136.2, 127.9, 127.9, 124.5, 124.5, 124.3, 124.3, 123.7, and
123.7.
(8) Linoleic acid: 13C NMR data (150 MHz, CDCl3) δC: 180.4, 130.2,
130.0, 128.0, 127.9, 34.1, 31.5, 29.6, 29.3, 29.1, 29.1, 29.0, 27.2, 27.2, 25.6,
24.6, 22.6, and 14.0
(9) Shimada, A.; Takeuchi, S.; Nakajima, A.; Tanaka, S.; Kawano,
T.; Kimura, Y. Biosci. Biotechnol. Biochem. 2000, 64, 187–189.
(10) Extracts were dissolved in ethanol solvent. Solutions were
pipetted onto Whatman #1 filter paper standardized at a rate of 0.15
mol/g filter paper. The solvent was allowed to evaporate from the filter
paper overnight. Treated filter papers were placed in the bottom of glass
vials (20 mm diameter ꢁ 50 mm) and moistened with water. Glass vials
were capped with aluminum foil punctured with pin holes for aeration.
Twenty Coptotermes formosanus workers (third instar or greater as
determined by size) and a single soldier were placed on each treatment.
Treatments were replicated four times and held separate from other
treatments to prevent vapor contamination. Each replicate originated
from a different C. formosanus colony to prevent a more sensitive colony
from overly biasing the results. Treatments were maintained at ca. 100%
RH and 27 °C in the dark. Filter paper receiving water alone served as
controls. It was previously determined that the solvent alone had no
discernible effect on termite mortality or filter paper removal.
Figure 2. Structure of R-terthienyl (3) and 2-(3,4-dihydroxybut-
1-yn-1-yl)-5-(penta-1,3-diyn-1-yl)thiophene (4).
Echinopsacetylene B (2) had the molecular formula
C31H40O3S, established by HRESIMS [m/z 515.2676
(MþNa)þ, Δ 8.0 mmu], indicating eighteen degrees of
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Org. Lett., Vol. 13, No. 23, 2011