Lithium bromide-DBU mediated synthesis of chlorophosphoramidate-activated morpholino nucleoside subunits

An efficient and rapid protocol for the synthesis of chlorophosphoramidate-activated morpholino sub-units has been developed. A unique combination of lithium bromide-DBU has been found to activate the 7'-hydroxyl toward the reaction. All the four morpholino units of adenosine, guanosine, cytosine, and thymine responded smoothly to the developed protocol. (C) 2012 Elsevier Ltd. All rights reserved.