Quinolonecarboxylic acid intermediaes useful in the preparation of antibacterial 6-fluouro-7-substituted-quinolonecarboxylic acids are prepared from 2-(iodo, bromo or chloro)-3-fluoro-4-(fluoro or chloro)-phenyl carboxylic acid or ester.
Quinolonecarboxylic acid intermediates useful in the preparation of antibacterial 6-fluoro-7-substituted-quinolonecarboxylic aids are prepared from 2-(iodo, bromo or chloro)-3-fluoro-4-(fluoro or chloro)-phenyl carboxylic acid or ester.
Concise formal synthesis of (−)-7-deoxyloganin via N-heterocyclic carbene catalysed rearrangement of α,β-unsaturated enol esters
作者:Lisa Candish、David W. Lupton
DOI:10.1039/c1ob05953j
日期:——
NHC catalysedrearrangement of α,β-unsaturated enol esters derived from formyl acetates and cyclopentyl annulated α,β-unsaturated acids provides the cyclopentapyranone core of (−)-7-deoxyloganin (1) with diastereo- and chemoselectivity in 6 steps starting from (−)-citronellal. The elaboration to the natural product has been investigated using two new approaches. The most successful intercepts our previous