Silicon-containing amino acids properties

Protein-modified siioxanes have recently drawn commercial attention. One major advantage is the possibility of combining film formation and moisture retention properties of proteins with lubricity and spreadability of silicones. Amino acid-modified silicones are obtained by the reaction of an alkali salt of an amino acid and an organo-modified polysiloxane containing epoxy groups (Fig. 10) [26]. These new copolymers show promising potential for cosmetic applications. 

In recent years, silicon-containing derivatives of proline have attracted considerable attention of chemists. The replacing proline by these unnatural amino acids, which are more stable towards proteolytic degradation, may increase the bioavailability of the structurally similar peptides without a modification of their conformational and biological properties (104). Currently, the Schdllkopf method is the only proven approach for the synthesis of silaproline cycle (105). Hydropyrazine is hydrolyzed under mild conditions to yield hydrochloride of 3-[(iodomethyl) (dimethyl) silyl] alanine methyl ester. The reaction of the latter with amine affords a product of the intramolecular cyclization of the 4,4-dimethyl-4-sila-proline methyl ester and its interaction with (t-Boc)20 gives rise to the corresponding N-t-Boc-silaproline methyl ester 133 (Scheme 24.17). 

---