Phase-transfer catalysts, functional group tolerance

Even the sterically encumbered o-tolyl bromide and the p-tolyl chloride were transformed into the corresponding arylamines in excellent yields. However, coupling of aryl chlorides stiU required an elevated temperature of 70 °C. Later on, the strong alkali base could be substituted by aqueous KOH in the presence of a phase-transfer catalyst, which resulted in higher functional group tolerance... 

Ju et al. (2006) carried out microwave synthesis of various azides, thiocyanates, and sulfones in an aqueous medium by reacting alkyl halides or tosylates with alkaU azides, thiocyanates, or sulfinates at 110 C for 20 min in the absence of any phase transfer catalyst, and a variety of reactive functional groups are tolerated. This is a practical, rapid, and efficient microwave synthesis method. 1.3 eq. of alkah azides, thiocyanates, or sulfinates are required to react with alkyl monohalide or alkyl monotosylates to give azides, thiocyanates, and sulfones, respectively. 

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