N-alpha-(9-Fluorenylmethyloxycarbonyl)-beta,beta-dimethyl-L-serine

beta,beta-Dimethylation of amino acids stabilizes appropriate peptides towards digestion by proteases. The hydroxyl function of this serine building block is unprotected, because acylation does not happen to tertiary alcohols during standard Fmoc/tBu coupling protocols. Reference: A General Method for Making Peptide Therapeutics Resistant to Serine Protease Degradation: Application to Dipeptidyl Peptidase IV Substrates; Kathryn R. Heard, Wengen Wu, Youhua Li, Peng Zhao, Iwona Woznica, Jack H. Lai, Martin Beinborn, David G. Sanford, Matthew T. Dimare, Amrita K. Chiluwal, Diane E. Peters, Danielle Whicher, James L. Sudmeier, and William W. Bachovchin; J. Med. Chem. 2013; 56: 8339-8351. dx.doi.org/10.1021/jm400423p. Total synthesis of the large non-ribosomal peptide polytheonamide B; Masayuki Inoue, Naoki Shinohara, Shintaro Tanabe, Tomoaki Takahashi, Ken Okura, Hiroaki Itoh, Yuki Mizoguchi, Maiko Iida, Nayoung Lee and Shigeru Matsuoka; Nature Chem. 2010; 2: 281-285. DOI: 10.1038/nchem.554.