Carbon‐13 chemical shift assignment of E‐stilbenyloxyalkanocarboxylic acids and their derivatives

Abstract

The 13C NMR spectra of 35 E‐stilbenols, E‐stilbenyloxyalkanocarboxylic acids and their esters and hydrazides have been calculated and fully assigned. The Ai empirical parameters of the p‐chlorostyryl, p‐bromostyryl, p‐alkoxycarbonylalkoxy, p‐carboxyalkoxy and p‐hydrazinecarbonylalkoxy groups have been calculated for use in the prediction of the chemical shifts of substituted benzenes and stilbenes.

Mass spectrometry of stilbenes: 4′‐Halo‐substituted metameric derivatives of (E)‐stilbenes

“…It is worth noting that the simultaneous removal from ions a of C O and HX molecules proceeds with high efficiency (Table 1, Scheme 1). The principal fragmentation patterns of 4-halo-substituted (E)-4-alkoxycarbonylalkoxystilbenes (3)(4)(5)(6)(7)(8)(9)(10) follow that of the 4-halo-substituted (E)-4-hydrazinecarbonylalkoxystilbenes (11-14) (Table 2, Scheme 2). As can be seen from the mass spectra of S14, (Fig.…”

“…It should be pointed out that the peaks of ions a are the main peaks in the mass spectra of f 1 0 , whereas the peaks of ions n are the base peaks in the mass spectra of 11-14. The differences in the relative abundances of the above ions allow the safe differentiation of metameric ethyl esters of (E)-4-halo-substituted 4-stilbenyloxyacetic acids (4, 6), methyl esters of (E)-4-halo-substituted 4-stilbenyloxy-a-propionic acids (7,9) and hydrazides of (E)-4-halo-substituted 4stilbenyloxy-a-propionic acids (12,14).…”

Synthesis and Physicochemical Properties of New Fluorescent Derivatives of Cytosine.

“…A series of sixteen new fluorescent N 4 -[(E)-stilbenyloxyalkylcarbonyl-cytosines (9)(10)(11)(12)(13)(14)(15)(16) and N 4 -(E)-stilbenyloxyalkylcarbonyl-1-methylcytosines (17)(18)(19)(20)(21)(22)(23)(24) have been synthesized in the reaction of the corresponding (E)-4-chlorocarbonylalkoxystilbenes (1)(2)(3)(4)(5)(6)(7)(8) with cytosine (or 1-methylcytosine) in boiling pyridine solutions, in the presence of a small amount of DMAP (Scheme 1). Noteworthy is the fact that the presence of the methyl substituent at the annular nitrogen atom N-1 of the pyrimidine ring of molecules (17)(18)(19)(20)(21)(22)(23)(24) changes the physicochemical properties of these compounds relative to those of 9-16.…”

“…The data from 1 H and 13 C NMR spectra of compounds 9-24 recorded in DMSO-d 6 and CF 3 COOD solutions are given in Tables III and IVa-d. Assignments of the 1 H and 13 C NMR resonances of these compounds were deduced on the basis of signal multiplicities, by comparison with literature data [13][14][15][16][17][18][19] and by the concerted application Mar-Apr 2006 337 D. Prukała 338…”

“…On the other hand, there is a wealth of published information on the fluorescent compounds of cytosine and cytidine [6][7][8][9][10], including their N-acyl derivatives [11]. This fact has stimulated the preparation of a series of N 4 -(E)stilbenyloxyalkylcarbonyl-cytosines (9)(10)(11)(12)(13)(14)(15)(16) and N 4 -(E)stilbenyloxyalkylcarbonyl-1-methylcytosines (17)(18)(19)(20)(21)(22)(23)(24) aiming at obtaining specific fluorescent modification of these compounds. The fluorescent moieties chosen for the study are (E)-stilbene, (E)-4'-chlorostilbene, (E)-4'-bromostilbene and (E)-4'-nitrostilbene.…”