1-Alkenesulfinyl Chlorides:  Synthesis, Characterization, and Some Substitution Reactions

Abstract

A number of 1-alkenyl sulfoxides bearing either a diphenylmethyl (DPM) or a p-methoxybenzyl (PMB) group have been prepared and exposed to the chlorine surrogate SO2Cl2. Through an oxidative fragmentation reaction, a new family of sulfur acid derivatives, 1-alkenesulfinyl chlorides, is generated. They can be characterized by IR spectroscopy before chemical capture with an alcohol. Ethenesulfinyl chloride (2a) and 1-propenesulfinyl chloride (2b), obtained from their corresponding DPM precursor, can be distilled at reduced pressure to afford ca. 90% pure material. NMR chemical shift comparison of various 1-alkenesulfinyl-containing compounds is made. 1-Alkenesulfinylmethyl phenyl(alkyl) ketones (6) can be prepared directly from sulfinyl chlorides 2 although decomposition and/or isomerization is sometimes extensive during purification.

Oxidative Fragmentations of 2-(Trimethylsilyl)ethyl Sulfoxides − Routes to Alkane-, Arene-, and Highly Substituted 1-Alkenesulfinyl Chlorides

“…[17] It was reported that p-methoxybenzyl and diphenylmethyl groups could be oxidatively cleaved from the sulfinyl unit, offering a collection of monosubstituted ethenesulfinic acid derivatives. As discovered above, the 2-(trimethylsilyl)ethyl functionality also promotes fragmentation and, accordingly, a number of sulfoxides were prepared for evaluation as precursors to sulfinyl chlorides.…”

“…Depending on the substrate(s) chosen, there is adequate opportunity to create highly substituted ethenesulfinyl entities, thereby fashioning a protocol that is complementary to the existing 1-alkenesulfinyl chloride preparation. [17] Scheme 3 Scheme 3 shows several reaction equations outlining the synthesis of the starting materials prepared for this section of the study. The addition of 2-(trimethylsilyl)ethanesulfenyl chloride (5) across the double bond of cyclopentene and dihydropyran afforded the expected β-chlorosulfide adducts, which were treated with base to eliminate readily HCl and create, after oxidation, sulfoxides 6.…”

“…They each exhibit AB character with a substantial difference in chemical shift, which is induced by the asymmetry of the proximate cis-sulfinyl unit. In previous observations, [17] methylene units trans to a sulfinyl group experience only small or nonexistent anisotropic effects.…”

“…Isolation of the resulting sulfinate ester facilitated full characterization to confidently ascertain the structure of the sulfinyl chloride. [17] Table 2 indicates the results from all oxidative fragmentation attempts.…”

“…The method is also useful for the generation of 1-alkenesulfinyl chlorides when the group to be severed is a p-methoxybenzyl or benzhydryl group. [17] 2-(Trimethylsilyl)ethyl sulfur functionalities play a variety of roles in organic chemistry. [18,19] Vinylic and acetylenic 2-(trimethylsilyl)ethyl sulfides are particularly useful as a source of α,β-unsaturated thiolates, [20Ϫ24] while Toru et al have shown that lithiated 2-(trimethylsilyl)ethyl sulfoxides serve as viable vinyl anion synthons.…”