When Ethyl Is Infinitely Different from Methyl: Double Addition of Lithiated Dithianes to Aromatic Carboxylates Revisited
作者:Roman A. Valiulin、Rudresha Kottani、Andrei G. Kutateladze
DOI:10.1021/jo060780f
日期:2006.6.1
benzoate does not produce the expected product of double addition, α,α-bis(alkyldithianyl) benzyl alcohol, for alkyls larger than methyl. Instead, the first step intermediate, i.e. 2-benzoylated dithiane, undergoes an electron-transfer reduction by the second molecule of the dithianyl anion. This reduction is followed by the ring-opening mesolytic fragmentation of the dithiane ring in the ketyl anion radical
Methyltriphenylphosphoniumtribromide acts as an efficient mild dethioketalization reagent with high selectivity for 2-phenyl and 2-vinyl 1,3-dithiannes versus 2-alkyl 1,3-dithiannes and without any secondary brominationreaction of the investigated substrates. The reaction was also successful with trimethylphenylammonium tribromide.
The anodicoxidation of α-keto and α-hydroxythloacetals provides an efficient way for the regeneration of α-diones and α-ketols, specially in the cases where chemical reactions are unsuccessful.
Anomalous C−C Bond Cleavage in Sulfur-Centered Cation Radicals Containing a Vicinal Hydroxy Group
作者:Zaiguo Li、Andrei G. Kutateladze
DOI:10.1021/jo035001z
日期:2003.10.1
1,3-dithianyl cationradicals having alpha-hydroxy-neopentyl or similar groups in position 2, which are generated via oxidative photoinducedelectrontransfer, undergo anomalous fragmentation necessitating refinement of the accepted mechanism. Experimental and computational data support a rationale in which proton abstraction from the hydroxy group in the initial cationradical does not cause a Grob-like