Iron-Mediated Segment Coupling of Alkenols with Acceptors via C-C Radical Translocation and Remote Oxidative 1,5/6-Hydrogen Atom Transfer.

Iron-mediated segment coupling followed by oxidative 1,5/6-hydrogen atom transfer (HAT) for synthesis of ε-oxo alkene derivatives is developed. This transformation involved translocation of the radical from H-to-C-to-C-to-C followed by the oxidation under MHAT conditions providing rapid access to 1,6/1,7-keto functionalized esters/ketone/sulfones/phosphonates/arenes. The different outcomes of coupling with acceptors could be explained by bond dissociation energies (BDEs), and mechanistic insights were gained through control experiments, including deuterium labeling studies.

Hydroalkoxylation-Initiated Cascade on Sulfone-Tethered Aryl Alkynols Gives Cyclic and Spiro-Heterocyclic β-Ketosulfones.

Serendipitous formation of cyclic β-ketosulfones is observed when sulfone-tethered arylalkynols are reacted with base. The reaction involves a base-promoted propargyl sulfone to the allene isomerization/intramolecular hydroalkoxylation/retro--Michael/6-- Michael addition cascade. Sulfone-tethered alkynyl acrylates gave stereoselective access to a diverse array of spirocyclic β-ketosulfone benzofuran/isochroman/indolines and sulfone-tethered bridged bicyclo[3.

Heteroatom-Assisted Regio- and Stereoselective Palladium-Catalyzed Carboxylation of 9-Allyl Adenine.

Strategy for the synthesis of acyclic nucleoside analogs of biological relevance via highly regio- and stereoselective C-H functionalization employing heteroatom-assisted palladium-catalyzed carboxylation of 9-allyl adenine is disclosed. Substrate scope with different carboxylic acids was performed giving decent to good yields of the desired products. The method also allowed for the synthesis of deuterated analogs.

Transposition of an acrylate moiety in TMSOTf-mediated reaction of alkynyl vinylogous carbonates gives heterocyclic dienes.

TMSOTf-mediated reaction of alkynyl vinylogous carbonates serendipitously gave 1,4-oxazepine and dihydropyran dienes transposition of an ethyl acrylate moiety involving intramolecular cascade Prins-type cyclization/retro-oxa-Michael reaction/cycloisomerisation. The developed atom-economical protocol selectively provides an double bond geometry. Dihydropyran dienes could be reduced diastereoselectively using EtSiH/TMSOTf or could be transformed into polycyclic heterocycles by Heck reaction.

Expeditious diastereoselective synthesis of medium ring heterocycle-fused chromenes via tandem 8/9-endo-dig and 8-exo-dig hydroalkoxylation-formal-[4 + 2] cycloaddition.

The first examples of highly diastereoselective tandem 8/9-endo-dig and 8-exo-dig hydroalkoxylation-formal-[4 + 2] cycloaddition are described for the synthesis of medium ring heterocycle-fused chromenes. TMS-alkynols preferred the exo-dig mode of hydroalkoxylation over the endo-dig mode leading to spiro-cyclic chromenes. The method could be used for the synthesis of linearly-fused ladder-like polyethers.