2014
DOI: 10.1039/c4nj01339e
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Conformational studies on substituted ε-caprolactams by X-ray crystallography and NMR spectroscopy

Abstract: The synthesis and conformational analysis of e-caprolactams containing a-COOMe group at the C-6 position is described. The influence of different C-2, C-6 and N substituents on ring conformation was studied using X-ray crystallography and NMR spectroscopy. The results provide evidence that all the analysed caprolactams adopt a chair type conformation with a planar lactam. In the 6-substituted caprolactam, the-COOMe residue prefers to reside in an equatorial position, but can be induced to occupy an axial orien… Show more

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Cited by 10 publications
(12 citation statements)
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“…4b) and 2b (Fig. 4c), the alkyne bonds are slightly distorted which is specified by the bond angles of 176. again stabilization via intramolecular S···O-contacts but involve also intramolecular S···S-contacts [24][25][26] leading to corresponding torsion angles around the two heteroaromatic and hydroxyl groups as particularized in Table 3. Probably owing to a packing induced distortion of the spacer elements, the alkyne bonds are not linear showing bond angles that range between 176.2 and 179.1 ° (with 4a deviating the most).…”
Section: Molecular Structuresmentioning
confidence: 99%
“…4b) and 2b (Fig. 4c), the alkyne bonds are slightly distorted which is specified by the bond angles of 176. again stabilization via intramolecular S···O-contacts but involve also intramolecular S···S-contacts [24][25][26] leading to corresponding torsion angles around the two heteroaromatic and hydroxyl groups as particularized in Table 3. Probably owing to a packing induced distortion of the spacer elements, the alkyne bonds are not linear showing bond angles that range between 176.2 and 179.1 ° (with 4a deviating the most).…”
Section: Molecular Structuresmentioning
confidence: 99%
“…However, the larger size of the ring combined with the planarity of the imino portion makes the system to behave similar to a cyclohexane, with the N–C 1 moiety replacing a single carbon of cyclohexane. 22…”
Section: Results and Discussionmentioning
confidence: 99%
“…The largest difference is observed for the C6-N1-C1-C2 torsion angle [59.3(2)° vs. 67.8 °] (Figure 8a). The additional Nα methyl group in 5 has also no signific a nt influence on the amide bond length compared with the caprolactam methyl ester (CSD code: BOLHER 49 ).…”
Section: Resultsmentioning
confidence: 99%
“…N-Bocprotection of ethyl ester 7 gave enantholactam 8 in 83 % yield. When we tried to saponify the Boc-protected caprolactam 12 49 using LiOH/H2O2, ring opening was observed and the respective Boc-protected adipic acid 13 could be recovered (Scheme 1c). Materials and methods.…”
Section: Methodsmentioning
confidence: 99%