The reactivity of methyl 4, 5-epoxy-(2E)-pentenoate (2) toward various aromatic nucleophiles in the presence of boron trifluoride etherate was examined. When benzene derivatives possessing an electron-donating substituent were employed, meta-substituted benzenes attacked only the 4-position of 2, while ortho- or para-substituted benzenes simultaneously attacked the 4- and 2-positions of 2.
Enzymatic Resolution of (.+-.)-5-Acetoxy-4-aryl-(2E)-pentenoate Derivatives
作者:Shin Tanikawa、Machiko Ono、Hiroyuki Akita
DOI:10.1248/cpb.53.565
日期:——
and 19 bearing a different aromaticsubstitution pattern, using lipase OF-360 from Candida rugosa was carried out. The absolute configurations of all hydrolyzed products and all unchanged acetates were found to be S and R, respectively. Moreover, the enantiomeric excess of the enzymatic resolution products from 9, 11, and 13 with the ortho-methoxyl group in the aromatic ring was higher than that of
Silica gel promotes the lactonization and the concomitant aryl rearrangement of 4-aryl-5-tosyloxy pentanoates (3c-j) to give γ-lactones along with complete inversion in high yields.
Lactonization of methyl 4-aryl-5-tosyloxy hexanoate 3 via a phenonium ion gave γ-lactone 4 selectively under thermodynamical conditions while it afforded δ-lactone 5 preferentially under kinetic conditions.