⁷⁷Se, ¹³C and ¹H NMR spectra of acyclic phenylselenenylalkanes and ‐alkenes and some of their selenoxides

Abstract

The 77Se, 13C and 'H NMR spectra of 57 mostly new compounds with phenylselenenyl groups attached to aeyc!lic alkanes, alkenes and phenylalkanes and of 10 corresponding selenoxides are reported. Substituent effects on the chemical shifts of these nuclei were determined and are discussed in terms of the conformation and configuration. The results suggest that, in contrast to PhSe-C-CSePh fragments, C -C --C S e chains prefer a gauche conformation. KEY WORDS -'Se NMR 13C NMR 'H NMR Phenylselenenylalkanes and -alkenes Selenoxides Substituent etrects Conformation I N T R O D U C T I O NRecently, we have published the NMR properties of a number of phenylselenenylcycloalkanes and discussed substituent effects on 77Se, 13C and 'H chemical shifts and conformational analyses of these compounds.' In this paper we describe an extension of this work to corresponding acyclic analogues. EXPERIMENTAL NMR measurements77Se NMR spectra were recorded at 76.3 MHz (Bruker AM-400) in 0.1-1 M CDCl, solution in 10 mm probes without ' H decoupling. Pulse widths were 30" and repetition rates 1-5 s. Spectral widths were 100 kHz and digital resolution was 6.1 Hz per point, i.e. less than 0.1 ppm. The reproducibility of 77Se chemical shifts is ca. kO.5 ppm if the temperature is kept constant carefully. 77Se chemical shifts are given relative to that of internal (or external) PhSeSePh (6 = 463), corresponding to CH,SeCH, (6 = 0).For all 'H and 13C NMR spectra including DEPT and COSY techniques standard Bruker software and parameters were used. 'H and I3C chemical shifts are referenced to tetramethylsilane (S = 0). IR spectra from CHCI, solutions were relcorded on Perkin-Elmer Model 221 and 13 10 spectrophotometers and electron impact (70 eV) mass spectra ton Varian MAT CH-5 and MAT 711 spectrometers; m/: values refer to fragments containing the "Se isotope. SynthesesSynthetic procedures were performed according to the Ether analogues (PhSeR; 1-29) . 2 diphenyl diselenide (PhSeSePh) was treated with sodium tetrahydroborate (NaBH,) and the respective alkyl halide (RX, X = CI, Br, I) or methanesulphonate (X = OSO,CH,) was added. The alkyl halides were commercially available and the methanesulphomates were prepared by reaction of alcohols with methanesulphonyl chloride. Acetal analogues [(PhSe),C(R,R'); 30-443 :3 diphenyl diselenide (PhSeSePh) was treated with NaBH, and boron tribromide (BBr,) was added to produce B(SePh), . After addition of the respective ketones the acetal analogues were isolated. Alkenyl derivatives [YhSeCH=CHR; 45-57] were obtained by elimination of PhSeH from the acetal analogues. The oxidation of selenides to form the selenoxides [PhSe(=O)R; 58-6714 was performed by bubbling ozone (from an ozone generator) through a solution of the respective selenide in chloroform at cu. -70°C and NMR spectra were recorded at -6O'C and higher until decomposition started. Only the selenoxides 58, 63 and 67 were stable enough to he isolated.

Chiral recognition of selenides and iodides by1H NMR spectroscopy in the presence of a chiral dirhodium complex

“…The selenides 2 and 3 have been prepared according to known procedures [10]. The syntheses of 4 and 5 were performed in analogy to 2 and 3 [10]. The iodides 6-8 have been purchased commercially (6 and 7 from Aldrich, 8 from Lancaster) and have been used without further purification.…”

“…The selenides 2 and 3 have been prepared according to known procedures [10]. The syntheses of 4 and 5 were performed in analogy to 2 and 3 [10].…”

Aqueous Phase One‐Electron Reduction of Sulfonium, Selenonium and Telluronium Salts

“…[34] Diphenyl methyl telluronium tetrafluoroborate [36] and ethyl methyl phenyl telluronium tetrafluoroborate [37] were prepared by literature methods. The following materials were prepared in analogy with published procedures (alkyl aryl selenides [38] and tellurides [39] ) and were used as reference compounds in the GC analyses: cyclohexyl phenyl selenide, [40] cyclohexyl phenyl telluride, [41] ethyl phenyl sulfide, [42] ethyl phenyl selenide, [43] ethyl phenyl telluride, [44] methyl phenyl selenide [45] and methyl phenyl telluride. [44] Preparation GC analyses were performed on a Varian 3400 GC fitted with a capillary Rescom SE 54 column and a flame ionization detector.…”

Comparing various chiral dirhodium tetracarboxylates in the dirhodium method

“…The synthesis and spectroscopic data of 2-butyl phenyl selenide (1) have been described by us before. 18 2-Butyl phenyl sulfide (2) 19 was produced by adding 2-iodobutane and thiophenol (PhSH) to a suspension of potassium carbonate in dry acetone (Williamson); yield was ca 70% after work-up and chromatographic purification. 2-Butyl acetate (3) is commercially available (Aldrich).…”