A mild and new procedure for the selective cleavage of an alkoxycarbonyl group (Boc, CBz) in N,N-dicarbamoyl-protected amino compounds is described. The method is based on the use of lithium bromide in acetonitrile and is compatible with a large range of other functionalities present in the substrates. Compared with other reported methodologies, the procedure is particularly useful for the Cbz-selective cleavage in N,N-Ts,Cbz-diprotected amines. A rationalization of the selectivity supported by ab initio calculations is also presented.
A selective, catalytic and practical method for removing a Boc group from several N,N′-diprotected amino acids and amine derivatives using iron(iii) salts as sustainable catalysts is described.
The consecutive treatment of N-Cbz amino protected compounds with LiHMDS and CbzCl provides a practical method for the preparation of N,N-benzyloxycarbamoyl (N,N-di-Cbz) derivatives in good yield. When alpha-amino acids are used the protection occurs without racemization. The method is compatible with a wide range of other functional and protecting groups. The procedure is also valid for the synthesis of mixed N,N-carbamoyl derivatives.
A New Selective Cleavage of N,N-Dicarbamoyl-Protected Amines Using Lithium Bromide. -Treatment of N,N-di-Boc-protected amines with LiBr offers a new, mild, and simple method to selective cleavage of one N-Boc group. Under these conditions no racemization is observed. LiBr is also effective for the selective deprotection of N-Boc-Tos and N-Cbz-Tos-protected amines. However, for selective deprotection of N-Boc-Ac and N-Boc-Cbz-protected amines the use of MgClO 4 is necessary. -(HERNANDEZ, J. N.; RAMIREZ, M. A.; MARTIN*, V. S.; J. Org. Chem. 68 (2003) 3, 743-746; Inst. Univ. Bio-Org., Univ. La Laguna, E-38206 La Laguna, Tenerife, Spain; Eng.) -Jannicke 24-167
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