31663-23-7Relevant academic research and scientific papers
Efficient Diastereoselective Syntheses of erythro- Or threo-a-Alkyl-β-hydroxy Sulfones by Reductions of α-Alkyl-β-keto Sulfones with TiCI4/BHg or LiEtsBH/CeCl3, Respectively
Marcantoni, Enrico,Cingolani, Simone,Bartoli, Giuseppe,Bosco, Marcella,Sambri, Letizia
, p. 3624 - 3630 (1998)
A stereoselective synthesis of erythro- and threo-α-alkyl-β-hydroxy sulfones by reduction of the corresponding α-alkyl-β-keto sulfones has been developed. The pivotal role in this methodology is played by the chelating or nonchelating properties of the Lewis acid employed. The strong chelating TiCl4 led to the erythro isomer in high diastereomeric excess in noncoordinating solvents (CH2Cl2) at -78 °C using BH3/py as reducing agent, while the nonchelating CeCl3 gave a high excess of the threo isomer in coordinating solvents (THF) at the same temperature using lithium triethylborohydride (LiEt3BH) as reducing agent. Moreover, this methodology has been successfully utilized for the synthesis of α-allyl-β-hydroxy sulfones, which are useful synthetic intermediates to obtain 2,5-disubstituted tetrahydrofurans by electrophilic cyclization.
