Hydrogenolysis sulfonate esters

BF3, AICI3, H2SO4, or alkyl halides) with an anhydrous solution of Bu N BHT in CH2CI2 This reaction has been successfully applied to the hydrogenolysis of halides and sulfonate esters to alkanes and to the anti-Markownikow hydration of olefins under liquid-liquid PTC conditions... 

This section lists examples of the hydrogenolysis of esters, R COOR — RH. For the conversion R COOR — R R" or RR" (R"=alkyl) see section 68 (Alkyls and Aryls from Esters). The reduction of esters of sulfonic acids (e.g. ROTs — RH) is included in section 160 (Hydrides from Halides and Sulfonates)... 

In the synthesis of hydroxamic acid 19a, having a free quaternary amino group (see Scheme 4.4), the intermediate sulfone 21 was synthesized by Pd-catalyzed reaction of phenol with p-bromo derivative 20 [24], Lithiation of 20, followed by nucleophilic addition to the A-Cbz imine of trifluoropyruvate 22 [25] afforded the a-CF3 a-amino acid derivative 23 in fair yields. Basic hydrolysis of the ester function gave the carboxylic acid 24, which was submitted to condensation with ()-15 n-hydroxylamine, affording hydroxamate 25. The subsequent hydrogenolysis of 25 afforded the target molecule 19a. 

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