Fe3+-Catalyzed transacetalization of 2-alkoxytetrahydrofurans with alcohols
摘要:
The transacetalization of 2-alkoxy-4-benzylidenctetraiiydrofurans with alcohols proceeds smoothly with the aid of Fe(ClO4)(3) catalyst. The catalyst reactivity is ordered as Fe(ClO4)(3)>Zn(ClO4)2>Mg(ClO4)(2). The present transacetalization provides an entry for various 2-alkoxytetrahydrofurans, which have potential as anticancer agents. (C) 2007 Elsevier Ltd. All rights reserved.
[GRAPHICS]The use of PdX2, CuX2 (X = OAc, OCOCF3, or Cl), and catechol together with (S,S)-4,4'-bisbenzyl-2,2'-bioxazoline under O-2 induces the asymmetric coupling of cinnamyl alcohols and vinyl ethers to give (R)-(+)-2-alkoxy-4-benzylidenetetrahydrofurans in 40-53% ee (79% yield). The present study provides implications for the so-called Wacker catalyst of PdX2 and CuX2, in terms of that the anionic ligands (X) of Pd and Cu interchange between two metals.