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Published on 03 April 2012 on http://pubs.rsc.org | doi:10.1039/C2OB25171J
to afford the corresponding [2 + 2]-cyclocondensation products
(7–9), (13) and (14) in quantitative yields which were sufficiently
pure as judged by 1 H NMR and ESI-TOF mass spectra
(Schemes 3 and 4). Similarly, macrocycles (10–12), (15) and
(16) were synthesised according to the above mentioned procedure
from (4S,5S)-1,3-dioxolane-4,5-dicarbohydrazide (4)
(Schemes 3 and 4).
Structures of the novel macrocycles were fully assigned on the
basis of 1 H NMR, 13 C NMR, 2D-NMR, VT-(variable temperature)
NMR, CD-spectroscopy, ESI- or APCI-TOF (atmospheric
pressure chemical ionisation) and FT-IR. APCI-TOF mass spectrum
for macrocycle (10) showed the expected molecular ion
peak (M + Na + ) at 599.1599 Da (Fig. 2, see ESI† for ESI-mass
spectra and fragmentation mechanisms). High resolution TOFmass
spectrometry data are given in Table 1. FT-IR spectrum for
macrocycle (10) showed the presence of a strong absorption
band at ν 1680 cm −1 corresponding to the stretching vibration of
the ν CvO and ν CvN. 1 H NMR spectra for the novel macrocycles
at ambient temperature in both DMSO-d 6 and DMF-d 7
showed broad signals suggesting conformational flexibility in
Scheme 4 [2 + 2]-Cyclocondensation products (13–16).
Scheme 3 [2 + 2]-Cyclocondensation products (7–12).
Fig. 2
APCI-TOF mass spectrum for macrocycle (10), from DMSO.
Table 1
High resolution TOF-mass data for the novel chiral macrocycles and isolated yields
Compound Molecular formula m/z Meas. m/z Error (ppm) Yield (%)
2 C 10 H 20 N 8 NaO 8 2M + Na + 403.1296 403.1277 4.7 57
4 C 10 H 20 N 8 NaO 8 2M + Na + 403.1296 403.1276 5.1 63
5 C 8 H 20 N 8 NaO 8 2M + Na + 379.1296 379.1285 3.1 88
6 C 8 H 20 N 8 NaO 8 2M + Na + 379.1296 379.1281 4 70
7 C 26 H 24 N 8 NaO 8 M+Na + 599.1609 599.1596 2.3 99
8 C 26 H 25 N 8 O 8 M+H + 577.1790 577.1782 1.4 99
9 C 38 H 33 N 8 O 8 M+H + 729.2475 729.2508 4.5 98
10 C 26 H 24 N 8 NaO 8 M+Na + 599.1609 599.1599 1.7 99
11 C 26 H 25 N 8 O 8 M+H + 577.1429 577.1450 3.6 99
12 C 38 H 31 N 8 O 8 M − H + b 727 b a,b 97
13 C 38 H 33 N 8 O 10 M+H + 761.2314 761.2292 2.9 99
14 C 50 H 42 N 10 NaO 8 M+Na + 933.3079 933.3048 3.4 99
15 C 38 H 32 N 8 NaO 10 M+Na + 783.2134 783.2113 2.6 98
16 C 50 H 43 N 10 O 8 M+H + 911.3260 911.3292 −3.5 99
17 C 24 H 25 N 8 O 8 M+H + 553.1844 553.1816 5 99
18 C 24 H 25 N 8 O 8 M+H + 553.1941 553.1954 −2.3 99
a Error value could not be estimated due to poor solubility and hence low peak intensity. b APCI-MS 2 .
This journal is © The Royal Society of Chemistry 2012 Org. Biomol. Chem., 2012, 10, 4381–4389 | 4383