Synthesis of â,â-Dimethylated Amino Acid Building Blocks Utilizing the 9-Phenylfluorenyl Protecting Group
نویسندگان
چکیده
Optically pure â,â-dimethylated amino acid building blocks with functionalized side chains have been prepared from D-aspartic acid. The dimethylation was accomplished by regioselective dialkylation of 9-phenylfluorenyl (PhFl)-protected aspartate diesters. The bulk of the PhFl protecting group also allowed for a variety of functional group manipulations to be carried out on the side chain without affecting the CR ester of the aspartate. As a result, the derivatives of the following novel amino acids were synthesized in this study: â,â-dimethyl-D-aspartic acid, â,â-dimethyl-Dhomoserine, 3,3-dimethyl-D-2,4-diaminobutyric acid, â,â-dimethyl-D-lysine, â,â-dimethyl-D-homoglutamate, â,â-dimethyl-D-ornithine, and 3,3-dimethylazetidine-2-carboxylic acid. The â,âdimethylated amino acids were synthesized in high enantiomeric excess as determined by coupling the novel building blocks to chiral reagents.
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