The Reaction of Aromatic Sulfonyl Azides with Trialkylboranes. An Unusual Synthesis of Aryl, Alkyl Sulfides

Abstract

Based on the reaction of alkyl azides with organoboranes to give secondary aminesl we decided to investigate the reaction of aryl sulfonyl Azsdes with trialkylboranes as a potential stereo and regiospecific route to sulfonamides as envisioned in eq. 1. The desired reaction did not occur. Thus, when a mixture of p-tolylsulfonyl

azide was reacted with tricyclohexylborane⁴ in re-fluxing toluene a gradual disappearance of the azide band at 2110 cm⁻¹ in the IR was observed with a concomitant appearance of a band at 2100 cm⁻¹ in dicating the presence of an intermediate in the reaction. Upon oxidation with alkaline hydrogen peroxide followed by purification by flash chromatography p-tolylcyclo-hexylsulfide was produced in 48% yield contaminated with very small amounts of bis-p-tolyldisulfide and the intermediate as as-certained by a small band at 2100 cm⁻¹ in the IR (eq. 2). The intermediate could not be isolated in pure form due to decomposition to the sulfide. The results of the preparation of arylalkyl-sulfides

by this route are given in Table I.