Eight-membered Rings with Four or More Heteroatoms

Ollmann, Richard R.

doi:10.1016/b978-008096518-5.00234-3

Cited by 2 publications

(1 citation statement)

References 142 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The structure of the compound could not be determined unequivocally by spectroscopies because of its highly complex but unique solution properties that will be discussed later. An X-ray single-crystal structure analysis revealed that the compound has the structure 4 ( n = 2 in the empirical formula) which possesses a hitherto unknown hexaselenacyclooctane ring (Figure ) . The compound adopts a typical crown-shaped conformation in the crystalline state.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Unique Properties of 4,8-Bis[bis(diethylamino)methylene]-1,2,3,5,6,7-hexaselenacyclooctane

et al. 1998

View full text Add to dashboard Cite

Treatment of 1-chloro-2,2-bis(diethylamino)ethene (1) with elemental selenium in refluxing benzene gave 4,8-bis[bis(diethylamino)methylene]-1,2,3,5,6,7-hexaselenacyclooctane (4) in 60% yield. The structure of 4 was determined by X-ray diffraction analysis. Compound 4 behaves as 2,2-bis(diethylamino)-2-ethylium-1-diselenocarboxylate (3) toward a range of reagents. Thus, 4 reacted with MeI, dimethyl acetylenedicarboxylate, and elemental sulfur, under mild conditions, to give the carbenium iodide 5a, the 1,3-diselenole 6a, and the dithiocarboxylate 2, respectively, in high yields, while the thermolysis in refluxing o-dichlorobenzene afforded the R-diselenoamide 7. Evidence for the dissociation of 4 into 3 in solution is provided by IR, UV/vis, and 1 H-, 13 C-, and 77 Se-NMR spectra.2,2-Bis(dialkylamino)-2-ethylium-1-dithiocarboxylates are a structurally interesting, unique class of inner salts. 1,2 In recent several years, we have been investigating the synthesis, structure, and reactivities of 2,2-bis(diethylamino)-2-ethylium-1-dithiocarboxylate (2) and the related compounds. 3 Particularly, we have found that 2 is easily obtained in high yield by treatment of 1-chloro-2,2-bis(diethylamino)ethene (1) 4 with elemental sulfur in the presence of triethylamine at room temperature. 3a,b We therefore thought that the reaction of 1 with elemental selenium would result in the formation of a new inner salt, 2,2bis(diethylamino)-2-ethylium-1-diselenocarboxylate (3). Unexpectedly, however, the reaction gave the title compound, 4,8-bis[bis(diethylamino)methylene]-1,2,3,5,6,7-hexaselenacyclooctane (4), in good yield. We report the X-ray diffraction analysis of 4, reactivities of 4 as the diselenocarboxylate 3 equivalent, and spectroscopic evidence for the formation of 3 in solution. Results and DiscussionSynthesis. Although the reaction of the enediamine 1 with sulfur took place smoothly to give 2 at room temperature in the presence of Et 3 N, the reaction with gray metallic selenium did not proceed under the same conditions. However, the reaction took place in refluxing solvents such as benzene, toluene, and chlorobenzene. Thus, heating 1 with selenium in the presence of Et 3 N in refluxing benzene for 5 h gave a 60% yield of a dark-red crystalline compound, mp 138.5-139.5 °C (dec.), that has an empirical formula of (C 10 H 20 N 2 Se 3 ) n . The structure of the compound could not be determined unequivocally by spectroscopies because of its highly complex but unique solution properties that will be discussed later. An X-ray singlecrystal structure analysis revealed that the compound has the structure 4 (n ) 2 in the empirical formula) which possesses a hitherto unknown hexaselenacyclooctane ring (Figure 1). 5 The compound adopts a typical crown-shaped conformation in the crystalline state. The CdC bond length (1.39 Å) of 4 is longer than those of the typical CdC bonds, and the torsion angle between the N-C-N and Se-C-Se planes is as large as 40.7°. These facts might suggest that the canonical structure 4′

show abstract

Section: Resultsmentioning

confidence: 99%