Chiral N-alkyl-2,4,6-triphenylpyridiniums as enantioselective triplet photosensitizers.: Laser flash photolysis and preparative studies
Chiral N-alkyl-2,4,6-triphenylpyridiniums as enantioselective triplet photosensitizers.: Laser flash photolysis and preparative studies
复制标题
DOI：
10.1021/jo020113w
复制
发表时间：
2002-07-26
影响因子：
3.6
通讯作者：
Sabater, MJ
中科院分区：
文献类型：
--
作者：
Alvaro, M;Formentín, P;Sabater, MJ
通过2，4，6-三苯基吡喃四氟硼酸盐离子与（1 R，2S）-（-）-去甲麻黄碱、（S）-（+）-2-（氨甲基）吡咯烷和（R）-（-）-1-环己基乙胺反应，合成了三种含手性烷基的N-烷基吡啶光敏剂。激光闪光光解允许检测被氢原子供体和电子供体淬灭的相应的三重激发态。用对映体纯的1，2-二氨基环己烷作为猝灭剂，观察到手性三重激发态的不对称猝灭。低对映体过量值（高达7%）的光化学环化5-甲基-4-己烯酸，其相应的γ-内酯使用这些手性N-烷基吡啶作为光敏剂测量。
Three N-alkylpyridinium photosensitizers having chiral alkyl groups have been prepared by reacting 2,4,6-triphenylpyrylium tetrafluoroborate ion with (1R,2S)-(-)-norephedrine, (S)-(+)-2-(aminomethyl)pyrrolidine, and (R)-(-)-1-cyclohexylethylamine. Laser flash photolysis allows detection of the corresponding triplet excited states that are quenched by hydrogen atom donors and electron donors. Asymmetric quenching of the chiral triplet excited state was observed using enantiomerically pure 1,2-diamino cyclohexane as quencher. Low enantiomeric excess values (up to 7%) were measured for the photochemical cyclization of 5-methyl-4-hexenoic acid to its corresponding gamma-lactone using these chiral N-alkylpyridinium as photosensitizers.