Methyl BTFP sulfone

Najera s methyl BTFP sulfone 319 has been applied in the synthesis of terminal olefins [106] (Scheme 103, cf Scheme 78 and the relevant text). Reaction of 319 (1 molar equivalent) with aldehydes or ketones (1.1 molar equivalent) could be conveniently carried out using P4-f-Bu (1.2 molar equivalent) or KOH-TBAB (9 molar equivalent) imder Barbier conditions. Some examples are shown in Table 25. 

Kocienski and co-workers discovered that metallated 1-phenyl-1//-tetrazol-5-yl sulfones (PT, 6) gave much better yields compared to its BT-substituted counterpart suggesting that the PT sulfone anions are less prone to self-condensation. Other heterocyclic derivatives, such as pyridine-2-yl (PYR, 7), l-tert-butyl-l//-tetrazol-5-yl (TBT, 8), and 3,5-bis(trifluoro-methyl)phenyl (BTFP, 9) sulfones" have also provided useful levels of stereoselectivity in the one-pot Julia-Kocienski olefination reaction. 

The synthesis of terminal alkenes from carbonyl compounds is a very important reaction in organic synthesis. Najera and co-workers found out that BTFP methyl sulfone is a good reagent to perform methylation reactions of carbonyl compounds through the Julia-Kocienski protocol. The reaction proved to be much more efficient when Barbier-type conditions were used. Example, alkene 90 was obtained in 45% yield by reacting sulfone 88 with diketone 89 in the presence of P4- -Bu in THF. For example, the sulfone 92, prepared from 84 by two-steps reaction in 81% yield, was converted to alkene 94 in 95% yield and 96 in 71% yield respectively. 

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See also in sourсe #XX -- [ ]

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