The invention of radical reactions. Part XXVII. Modified Julia Synthesis of Olefins Using radical deoxygenation

Stenotrophomonas maltophilia OleC-Catalyzed ATP-Dependent Formation of Long-Chain Z-Olefins from 2-Alkyl-3-hydroxyalkanoic Acids

The bacterial pathway of olefin biosynthesis starts with OleA catalyzed "head-to-head" condensation of two CoA-activated long-chain fatty acids to generate (R)-2-alkyl-3-ketoalkanoic acids. A subsequent OleD-catalyzed reduction generates (2R,3S)-2-alkyl-3-hydroxyalkanoic acids. We now show that the final step in the pathway is an OleC-catalyzed ATP-dependent decarboxylative dehydration to form the corresponding Z olefins. Higher kcat /Km values were seen for substrates with longer alkyl chains. All four stereoisomers of 2-hexyl-3-hydroxydecanoic acid were shown to be substrates, and GC-MS and NMR analyses confirmed that the product in each case was (Z)-pentadec-7-ene. LC-MS analysis supported the formation of AMP adduct as an intermediate. The enzymatic and stereochemical course of olefin biosynthesis from long-chain fatty acids by OleA, OleD and OleC is now established.

Facile preparation of benzo[4,5]thieno[2,3-b]pyridines and naphtho[b-4,5]thieno[2,3-b]pyridines via the reaction of Barton esters and benzynes

Titled compounds were prepared in a one-pot synthesis by generating symmetrically substituted benzyne intermediates by the diazotization of anthranilic acids in the presence of Barton esters. Unsymmetrically substituted aryne either gave mixtures of regioisomers or failed. However, nitro and methyl derivatives of titled compounds could be obtained as single products using appropriately substituted Barton esters.