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Recherches sur la formation et la transformation des esters LXXXII [1]. Sur la différenciation entre structures δ 2 ‐amino‐2 ou imino‐2 dans des composés S, N‐hétérocycliques pentagonaux et hexagonaux à cycle par ailleurs saturé
Author(s) -
Rabinowitz Joseph
Publication year - 1969
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.19690520125
Subject(s) - chemistry , protonation , double bond , stereochemistry , nmr spectra database , sulfuric acid , aromaticity , singlet state , proton nmr , medicinal chemistry , crystallography , molecule , spectral line , polymer chemistry , excited state , organic chemistry , ion , physics , astronomy , nuclear physics
Comparison of the NMR. spectra in CDCl 3 of the heterocyclic bases obtained from the cyclisation of ω‐(N‐thiocarbamoylamino) ethyl (or propyl)‐alcohols (or their orthophosphoric or sulfuric monoesters) to those of model compounds II ( n = 1 or 2) and III ( n = 1 or 2) has shown that: (1) In the case of five membred rings the CN double bond is always endocyclic (Ib, n = 1) should R be aromatic, araliphatic or aliphatic; (2) In the case of six membered rings the CS double bond is cnclocyclic when R is aliphatic or araliphatic (Ib, n = 2), and exocyclic when R is aromatic (I a, n = 2), with the exception of 2‐(o‐carboxyphcnylamino)‐dihydro‐δ 2 ‐ m (Ib, n = 2, K = o ‐carboxyphcnyle). In CF, COOH, all five membered rings (I b, n = 1) show a triplet for the C‐4 methylenic protons, whereas all the six membered rings (Ia or I b, n = 2) with the exception of I b, n = 2, R = o‐carboxyphenyle, are represented b y a double triplet for the C‐4 protons (samt. protonated spccics). Only one triplet is observed when the 3 position is substituted. Thiocarbamoylation of hydrazinoethanol or its orthophosphoric or sulfuric monoesters canoccur at either of the two nitrogen atoms, thus yielding upon cyclization five‐ (IT′) or six‐membered rings (Va or Vb). The NMR spectra of compounds I V in (CIl,), SO show a singlet for 2 amino pro‐tons (3‐amino) and there is no further structural problem. The NMR spectra of compounds T′ in (CT), SO show a triplet for one amino proton coupling with the neighboring methylenic protons. I n this case, mode1 compounds are needed to assign the position of the CN double bond ( e x cyclic V a or cndocyclic V b). When R = o‐carboxyphenylc, the CN double bond is probably endoc, yclic (Vb) because this ccimpound and 2‐(o‐carboxyphenvlarnino)‐dihydro‐δ 2 have very similar UV spectra.