Vinyl Carbanions. Part 36.. Synthesis of 3-deoxy-D-manno-2-octulosonic acid (KDO) and derivatives

✍ Scribed by Angelika Esswein; Rainer Betz; Richard R. Schmidt

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: German
• Weight: 728 KB
• Volume: 72
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19890720205

✦ Synopsis

The 8-C-lithiated acrylamide 3A has been proven to be an ideal pyruvate 8-carbanion equivalent useful in a highly diastereoselective KDO synthesis. The starting material 3 was prepared from pyruvate diethyl acetal in four convenient steps. Direct lithiation with 2 equiv. of LDA generated the dilithiated species 3A quantitatively. Reaction with 2,3 :4,5-di-O-isopropyIidene-o-arabinose (11) was highly o-manno-selective. The product 12 was obtained readily from the reaction mixture via crystallization. Ring closure to the butenolide 13, subsequent PhS-group removal with Bu,SnH and pyridinium bromide, and hydrogenolytic debenzylation afforded the known butenolide 19; this KDO precursor gives KDO in two convenient steps. Butenolide 19 was also transformed via two high-yielding steps into the 4,5 :7,8-di-O-cyclohexylidene-KDO derivative 22, a valuable starting material for KDO a -glycoside syntheses. ') Part 35: [9]. 2, ') Taken in part from the Ph. D. thesis of A . E . [13] and R.B. [12]. For a preliminary publication of part of this work, see [3].