Methylsulfanyldifluoromethylphosphonate

Desymmetrization of meso-Diols. BTM-catalyzed de-symmetrization of meso-diol lobelanidine has been employed as the key step in an asymmetric synthesis of alkaloid lobeline (eq 6).5 

Related Reagents. 7-Chloro-l,2-dihydro-2-phenyl-imidazo [l,2-a]quinoline (Cl-PIQ), / -Enantiomer [863319-04-4]) 3,4-Dihydro-2-phenyl-2//-pyrimido[2, l-fi]benzothiazole (HBTM) 2-(A -Benzyl-7V-methylaminomethyl)- 1-methylpyrrolidine (/ -Enantiomer [540474-12-2], 5-Enantiomer [208833-00-5]) 4-Dimethylaminopyridinyl(pentaphenylcyclopentadienyl)rron (C5 Phs-DMAP, / -Enantiomer [187682-64-0], 5-Enantiomer [187596-69-6]).  

Selectivity factor is defined as s = A(fast-reacting enantiomer)/A(slow-reacting enantiomer). Both conversion C and selectivity factor s are calculated firom ee s of the product (ecp) and the recovered starting material (eesm) according to Kagan s equations 1 C=eesm/(eep + eesm) 5=ln[(l-C)(l-eeA)l/lnI(l - O(l-HeeA)]. 

Ohashi, K. Oriyama, T., Chem. Lett. 1999, 265. 

Ximin Li, Hui Jiang, Vladinmr B. Birman Washington University, St. Louis, MO, USA 

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The phosphonate is then converted into diisopropyl methyl-sulfanyldichloromethylphosphonate upon treatment with sul-furyl chloride or Atchlorosuccinimide and the latter is treated with hydrogen fluoride/triethylamine/zinc hromide to afford diisopropyl methylsulfanyldifluoromethylphosphonate (eq 2). 

Radical Addition to Alkenes. Diisopropyl methylsulfanyl-difluoromethylphosphonate is a precursor of phosphonodifluoro-methyl radicals. The radical addition product is generated when diisopropyl methylsulfanyldifluoromethylphosphonate is treated with tributyltin hydride in the presence of /l/5Af(eq 3). A similar reaction is also observed with the analogous diethyl methylsul-fanyldifluoromethylphosphonate (eq 4). 

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