Catalytic ring expansion of vinyl oxetanes: Asymmetric synthesis of dihydropyrans using chiral counterion catalysis
Acid Showdown! The first catalytic ring expansion of vinyl oxetanes to 3,6-dihydro-2H-pyrans is described. Copper(II) triflate emerged as the best catalyst for this new transformation, which has broad scope as demonstrated by the eighteen examples included. The symmetric vinyl oxetane substrate can be asymmetrically desymmetrized when using either chiral Lewis or Bronsted acids as catalysts. Copyright
Guo, Boying,Schwarzwalder, Gregg,Njardarson, Jon T.
supporting information; experimental part
p. 5675 - 5678
(2012/07/03)
Enzymatic approach to enantiomerically pure 5-alken-2,4-diols and 4-hydroxy-5-alken-2-ones: Application to the synthesis of chiral synthons
Enantiomerically pure 1,3-diols 1-3 were obtained by a chemoenzymatic approach (lipase PS from Burkholderia cepacia). These diols were converted into useful chiral synthons, which could be considered homologues of glyceraldehyde and glyceric acid acetonid
Abate, Agnese,Brenna, Elisabetta,Costantini, Alessia,Fuganti, Claudio,Gatti, Francesco G.,Malpezzi, Luciana,Serra, Stefano