Wittig condensation chain extension

Other alternatives for chain extension have been developed. Wittig condensation between the dialdose derivative 194 and the (PPI13I) monosaccharide derivative 195 occurs with complete stereoselectivity, forming a cis linkage. Compound 196 is the precursor of a deaminotunicamine derivative.399... 

Seebach completed the first synthesis of optically active 9 as depicted in Scheme 4.2. ° Protected alcohol 10, available from an optically active p-hydroxy butyric ester, was alkylated with 2-lithio-1,3-dithiane. Deprotonation of this material followed by formylation with DMF then afforded 11. Chain extension to the unsaturated ester was accomplished via a Wittig condensation and deprotection to produce the monomeric unit 12 in 57% overall yield from 10. Double lactonization under Mitsunobu conditions (DEAD-PhjP) afforded a 60%... 

The functionalized carbocycle (8) has been prepared from D-glucose (carbon atoms numbered) by Wittig chain extension and intramolecular aldol condensation, lo... 

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