Practical Synthesis of Aromatic Dithiocarbamates

Abstract

Oxidation-sensitive N,N-diaryl dithiocarbamates (DTCs) are synthesized in good yields by the generation of metal amide salts from N-benzoyl precursors, followed by addition of CS₂. para-Substituted diphenylamines are prepared by electrophilic aromatic substitution of diphenylbenzamide and saponification. Deacylation of electron-rich species such as bis(p-dimethylaminophenyl)benzamide is challenging because of the oxidative sensitivity of the anionic intermediate but could be achieved in good yield by using n-BuLi to generate a hemiaminal adduct, prior to acidification. The N,N-diaryl DTCs are stable as alkali salts and can be used to produce densely packed monolayers on gold surfaces.

GRAPHICAL ABSTRACT

Keywords:

• Benzamide
• deprotection
• dithiocarbamate
• oxidation sensitive

Notes

^a Conversion determined by ¹H NMR.

^b Isolated yield.

^a 1.0–2.5 equiv.

^b Isolated yields unless stated otherwise.

^c Hydrochloride salt, neutralized with one equivalent of n-BuLi or dimsyl-Li.

^d Reaction conditions: (i) 50 °C for 5 h, then −78 °C; (ii) CS₂ (5–10 equiv), warmed to rt.

^e Yield after a single precipitation.