Monoprotection of Diamondoid Diols

Significance

The authors describe a method of selective protection of symmetric diamondoid diols enabling the synthesis of unsymmetrical diamondoid derivatives. The authors first monoprotect diol 1 as a trifluoroethanol (TFE) ether in good yield. Next they convert the unprotected alcohol into an amine protected as an amide using the Ritter reaction. Exchange of the TFE ether protected alcohol to the trifluoroacetate-protected alcohol, followed by hydrolysis yields 6. A Koch-Haaf reaction followed by esterification, purification, and subsequent hydrolysis yields difunctional amino acid 8.