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Triaziridine 7. Mitteilung . Stabile pyramidale Konfigurationen an den Stickstoff‐Atomen von Dialkyl‐und Trialkyl‐triaziridinen
Author(s) -
Hilpert Hans,
Hoesch Lienhard,
Dreiding André S.
Publication year - 1987
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19870700216
Subject(s) - chemistry , substituent , crystallography , stereochemistry , nmr spectra database , nuclear magnetic resonance spectroscopy , nitrogen atom , spectral line , alkyl , physics , organic chemistry , astronomy
Stable Pyramidal configurations at the Nitrogen Atoms of Dialkyl‐and Trialkyl‐triaziridines Stereochemical features of the recently synthesized nine samples of di‐ and trialkyl‐triaziridines, namely the 1,3‐cyclopentylen‐(series a ) and the two stereoisomers of the diisopropyl derivatives (series b and c ), containing as the third substituent an H‐atom ( 2 ), a CH 3 group ( 3 )or a CH 2 OH group ( 4 ), were elaborated on the basis of the 1 H‐, 13 C‐, and 15 N‐NMR spectra. The three N‐atoms of the saturated N 3 ‐homocycle were found to be stable to pyramidal inversion in all cases. According to their NMR spectra, 2 – 4 of the series a and b possess twofold symmetry ( C s ), while 2 – 4 of series c are asymmetric. Thus, series c has the trans ‐configuration at N(2)/N(3) and, consequently, the cis ‐configuration at N(1)/N(2), while series a and b have the cis ‐configuration at N(2)/N(3) and ‐since the all‐ cis ‐arrangement is excluded‐the trans ‐configuration at N(1)/N(2). The asymmetry of the trans ‐configurated 2c turned into twofold symmetry ( C 2 ), when a little CF 3 COOH was added. The 1 H‐ and 13 C‐NMR data of series b and c of our alkyl‐triaziridines exhibit a shielding effect, according to which there are two types of i‐Pr groups, i‐Pr(a) and i‐Pr(b). They differ in the NMR signals of the H‐ and the C‐atoms of their CH groups: the H‐atoms of i‐Pr(a) are more deshielded by 0.75–1.111 ppm and its C‐atoms are more shielded by 10.0–160.0 ppm as compared to the corresponding atoms of i‐Pr(b). i‐Pr(a) is cis (on the N 3 ‐homocycle) to a large substituent (such as i‐Pr, Me, CH 2 OH) and to a lone pair, while i‐Pr(b)is cis only to a small (H) or to no substituent and to one or two lone pairs. An analogous effect appears in the NMR signals of the CH 3 and CH 2 OH groups at N(1) of 3 and 4 in the series b and c .