Aminosilicones without Protecting Groups: Using Natural Amines

Aminosilicones are widely used in commerce for their own interesting properties and as intermediates to organofunctional silicones. Traditional methods for their preparation involve hydrosilylation of allylamine derivatives or nucleophilic displacement of alkyl halides by amines. The former process is compromised by the need for protecting group chemistry, while the preparation of primary amines in the latter case is frequently complicated by overalkylation. Thiol–ene reactions, including to vinylsilicones, are very clean, byproduct-free click reactions. We report that telechelic or pendent vinylsilicones can be converted to the analogous aminoalkylsilicones by the photoinitiated, radical-mediated thiol–ene addition of the natural product cysteamine, which is “naturally” protected in its ammonium form. The product amino sulfide silicone polymers may optionally contain residual vinyl groups. Expensive transition metal catalysts are not required; indeed, platinum catalysts are inhibited by the sulfur-modified aminosilicone products.