Arylation of n-Hexylthiol and n-Hexyl Phenyl Sulfide Using Diphenyl­iodonium Triflate: Synthetic and Mechanistic Aspects - Application to the Transformation of n-Hexylthiol to n-Hexylselenide

Abstract

n-Hexyl diphenylsulfonium triflate has been efficiently prepared from n-hexylthiol and diphenyliodonium triflate and has been efficiently transformed to n-hexyl selenide.

arylations - thiols - desulfurization - selenium - substitutions

References and Notes

<A NAME="RG37405ST-1">1</A> Krief A. Dumont W. Robert M. Chem. Commun.  2005,  2167 

<A NAME="RG37405ST-2A">2a</A> Shah A. Pike VW. Widdowson DA. J. Chem. Soc., Perkin Trans. 1  1997,  2463 

<A NAME="RG37405ST-2B">2b</A> Kitamura T. Matsuyuki J. Taniguchi J. Synthesis  1994,  147 

<A NAME="RG37405ST-3A">3a</A>

Arylation of n-hexylthiol has been also achieved in toluene by in situ formation of the corresponding thiolate using either potassium (18% yield of 3a) or better cesium (65% yield of 3a) hydroxide.

<A NAME="RG37405ST-3B">3b</A>

We found that diphenyliodonium tetrafluoroborate and diphenyliodonium chloride also allow, under identical experimental conditions, the arylation of hexylthiolate (79% and 64% yield, respectively).

<A NAME="RG37405ST-3C">3c</A>

Thiophenol has been previously arylated with diaryl iodonium salts in the presence of tributylamine to produce directly triaryl sulfonium salts. [3d]

<A NAME="RG37405ST-3D">3d</A> Crivello JV. Lam JHW. Synth. Commun.  1979,  151 

<A NAME="RG37405ST-4">4</A>

We have proved in many instances that iodobenzene is formed as a by-product in these reactions (70-84% isolated yield).

<A NAME="RG37405ST-5A">5a</A>

Reaction performed under argon.

<A NAME="RG37405ST-5B">5b</A>

Reaction initiated after sonication and bubbling argon into the solution.

<A NAME="RG37405ST-6">6</A>

Those reactions are being investigated in detail and will be reported in the full paper.

<A NAME="RG37405ST-7">7</A> Lockhart TP. J. Am. Chem. Soc.  1983,  105:  1940 

<A NAME="RG37405ST-8">8</A> Crivello JV. Lam JHW. J. Am. Chem. Soc.  1978,  43:  3055 

<A NAME="RG37405ST-9A">9a</A> Breckenridge JG. Lewis RW. Quick LA. Can. J. Res. Sect. B  1939,  17:  258 

<A NAME="RG37405ST-9B">9b</A> Hoste J. Anal. Chim. Acta  1950,  4:  23 

<A NAME="RG37405ST-10">10</A>

We found that Cu(I) triflate is a poorer catalyst for the arylation of n-hexyl phenyl sulfide (3a) using diphenyliodonium tetrafluoroborate (4a) instead of the corresponding triflate 4b (4a:3a:CuOTf ratio: 1:1:5):
(i) 110 °C, 0.2 h, 5a: 72%, 3a: 24% or (ii) 80 °C, 1.5 h, 5a: 13%, 3a: 73%; compare to Scheme [3] , Table [1] , entries e
and g.