the (4S)-4-hydroxy-5-(4′-methoxyphenyl)-2(E)-pentenoate 5 using the AgNO3/MS 4 Å/MeNO2 system was accomplished along with complete inversion at the C4-position, and the synthesis of the intermediate (4S)-7 for the chiral synthesis of (−)-anisomycin 6 from (4S)-7 based on osmium tetroxide-catalyzed stereoselective hydroxylation was achieved.
(4所述的立体选择性转化- [R)-5-羟基-4-(4'-甲氧基苯基)-2(É)-pentenoate 4到(4小号)-4-羟基-5-(4'-甲氧基苯基)-2-使用AgNO 3 / MS 4Å/ MeNO 2系统完成(E)-戊烯酸酯5以及在C 4位完全转化,并合成中间体(4 S)-7用于手性合成(-基于四氧化os催化的立体选择性羟基化反应,获得了(4 S)-7的)-茴香霉素6。
Reaction of Methyl 4,5-Epoxy-(2E)-pentenoate with Arylcopper Reagents.
作者:Shinji NAGUMO、Shigeyuki IRIE、Hiroyuki AKITA
DOI:10.1248/cpb.44.675
日期:——
The reaction of methyl 4, 5-epoxy-(2E)-pentenoate (1) with various arylcopper reagents was studied. Basically, all arylcopper reagents react with 1 in SN2 fashion. However, addition of BF3 causes reversal of the regioselectivity, which can be rationalized in terms of a two-step conversion by way of methyl 4-bromo-5-hydroxy-2-pentenoate (5).
The reaction of methyl (E)-4,5-epoxypent-2-enoate with arylcopper: the unique role of boron trifluoride in determining regioselectivity
作者:Shinji Nagumo、Shigeyuki Irie、Hiroyuki Akita
DOI:10.1039/c39950002001
日期:——
Excess BF3 causes regioselectivity reversion in the reaction of methyl 4,5-epoxypent-2-enoate 1 with Ph2CuLi; this is rationalised by a two step conversion via methyl 4-bromo-5-hydroxypent-2-enoate 5.
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.