The convergent synthesis of caryophyllose, a new C-4 branched dodecose isolated fromPseudomonascaryophylli, is described from two monosaccharidic precursors. The key step is the diiodosamarium-promoted coupling of two six-carbon fragments: an acid chloride and a cyclic ketone.
The C-4 branched monosaccharide caryophyllose 2a was synthesized by a convergent approach relying on the coupling of metalated dithioacetal 4b with ketone 3. Combined use of n-BuLi and t-Bu-ONa as deprotonation system for 4b turned out to be decisive for the success off this coupling. (C) 2000 Elsevier Science Ltd. All rights reserved.