AMINO-ACID BASED DIASTEREOSELECTIVE SYNTHESIS OF ELSAMINOSE

Optically pure (+)-elsaminose (2), the amino sugar contained in the an titumour antibiotic elsamicin A, has been synthesized in eight steps ( 26% overall yield) from known building blocks derived from glycine, L- valine, and L-threonine. Direct and selective construction of the key intermediate 6, with the complete backbone and the proper stereochemic al configuration, is accomplished by a syn-aldol type reaction between lithiated Schollkopf's bislactime ether 5 and a 1,3-dioxolane-4-carbo xaldehyde (-)-3. Copyright (C) 1996 Elsevier Science Ltd.