Pyrolysis of (2-Phenylethyl)phenylsulfonium Ylides

Abstract

In order to obtain information concerning the reaction mechanism of the pyrolysis of sulfonium ylides bearing a substituted phenyl group on the 2-position in the S-ethyl group of ethylphenylsulfonium ylide, (2-phenylethyl)phenylsulfonium bis(methoxycarbonyl)methylide (1) and dicyanomethylide (2) were subjected to pyrolysis in benzene. The reaction rates of 1 and 2 at 140 °C were 6.0- and 3.2-times faster than those of ethylphenylsulfonium bis(methoxycarbonyl)methylide and dicyanomethylide, respectively. The activation parameters for 1 were ΔH‡ = 125 kJ mol−1 and ΔS‡ = −3.8 J K−1 mol−1, while those for 2 were ΔH‡ = 124 kJ mol−1 and ΔS‡ = −2.5 J K−1 mol−1. Substituent effects on the β-phenyl groups in 1 and 2 afforded positive Hammett ρ-values: ρ = 0.49 (γ = 0.997) and ρ = 0.26 (γ = 0.993), respectively. From the obtained results, it was suggested that the pyrolysis proceeds through essentially a concerted intramolecular cis-elimination inclined toward a slightly carbanion-like type from an E1-like type by introducing a phenyl substituent at the 2-position of the ethyl group in the ethylphenylsulfonium ylide.

Responses of polar organic compounds to different ionic environments in aqueous media are interrelated

“…It can be seen from Table 1, however, that NaClO 4 may salt-out certain organic compounds (6 out of 17). The salting-out effects of NaClO 4 on tris(glycinato)cobalt(III) and on several polycyclic aromatic hydrocarbons were also reported by Yoshimura 28 and Schlautman et al 29 The ability of NaClO 4 to form an aqueous two-phase system in mixtures with polyethylene glycol 30,31 may also be viewed as resulting from the salting-out effect of NaClO 4 . The salting-out and salting-in effects of NaClO 4 are solute specific and may be explained by direct or water mediated ion-solute interactions.…”

A Common, Facile and Eco‐Friendly Method for the Reduction of Nitroarenes, Selective Reduction of Poly‐Nitroarenes and Deoxygenation of N‐Oxide Containing Heteroarenes Using Elemental Sulfur

“…[9] Other non-metal methods in-volving the use of sulfur-derived reagents (e.g. sulfurous acid, [10a] SO 2 ,[10b] sulfur monoxide, [11] trimethyl(or triethyl)amine-SO 2 complex, [12] di-n-propyl sulfoxylate [13] and CS 2 [14] ), phosphorus-derived reagents (e.g. PCl 3 [15] and PPh 3 at high temperatures [16] ) and other organic compounds [17,18] have been also reported for the deoxygenation of N-oxide containing heteroarenes.…”

ChemInform Abstract: Analogues of Sialic Acids as Potential Sialidase Inhibitors. Synthesis of C6 and C7 Analogues of N‐Acetyl‐6‐amino‐2,6‐dideoxyneuraminic Acid.

“…explored for the transformation of the D-glucosamine derivative 19 [ 121 into an appropriate ester of the corresponding uronic acid (Scheme I). Catalytic oxygenation of 19 [12] [13], followed by esterification either with Me1 or with CH,N, and by acetylation, gave 21 in 87% yield [I41 for batches of 1-5 g. Larger batches required large amounts of the Pt catalyst and longer reaction times, particularly when the catalyst was reused'). We preferred to transform 20, readily available from 19 by tritylation, acetylation, and detritylation [15], into the t-Bu ester 22 by oxidation with CrOJpyridine in the presence of Ac, (62% from 19).…”