Enzymatic Synthesis of Optically Active a-Hydroxybenzylpyridines
摘要:
Synthesis of optically active alpha-hydroxybenzylpyridines by asymmetric reduction of benzoylpyridines and benzoylpyridine N-oxides with baker's yeast, and enantioselective esterification of racemic alpha-hydroxybenzylpyridines by use of lipase PS have been described.
铬(II)水溶液Cr aq 2+与苯甲酰吡啶氧化物(BPO)的反应比与先前探索的其他吡啶N-氧化物的反应要快得多。在伪一级反应条件下用过量的任何一种试剂研究了动力学。在这两种条件下,主要动力学项均表现出对限制试剂的一阶依赖性,以及对过量试剂的二阶依赖性,即k Cr = k 2 Cr [BPO] [Cr aq 2+ ] 2(过量的Cr aq 2+)并且k BPO = k 2 BPO[Cr aq 2+ ] [BPO] 2(过量BPO),其中k 2 Cr =(6.90±0.27)×10 4 M -2 s -1和k 2 BPO =(3.32±0.28)×10 5 M -2 s -1在0.10 M HClO 4中。速率常数k 2 Cr包含与[H + ]独立和[H + ]催化的路径相对应的项。在提出的机制中,最初形成的Cr aq(BPO)2+参与Cr aq的平行氧化2+和降低BPO。后一反应为Cr(
Iodo- or 2-bromopyridine N-oxides were readily magnesiated with i-PrMgCl·LiCl via the iodine or bromine−magnesium exchange. The bromine adjacent to pyridineN-oxide (at the 2- or 6-position) can be regioselectively magnesiated in the presence of other position substituted halogens. This method was tested in various substituted pyridineN-oxide systems, and has been successfully applied to the total
Kinetics and mechanism of the reaction of Cr(ii) aqua ions with benzoylpyridine N-oxide
作者:Mingming Cheng、Andreja Bakac
DOI:10.1039/b701236e
日期:——
Aqueous chromium(II) ions, Craq2+, react with benzoylpyridine oxide (BPO) much more rapidly than with other pyridine N-oxides previously explored. The kinetics were studied under pseudo-first order conditions with either reagent in excess. Under both sets of conditions, the major kinetic term exhibits first order dependence on limiting reagent, and second order dependence on excess reagent, i.e.kCr
铬(II)水溶液Cr aq 2+与苯甲酰吡啶氧化物(BPO)的反应比与先前探索的其他吡啶N-氧化物的反应要快得多。在伪一级反应条件下用过量的任何一种试剂研究了动力学。在这两种条件下,主要动力学项均表现出对限制试剂的一阶依赖性,以及对过量试剂的二阶依赖性,即k Cr = k 2 Cr [BPO] [Cr aq 2+ ] 2(过量的Cr aq 2+)并且k BPO = k 2 BPO[Cr aq 2+ ] [BPO] 2(过量BPO),其中k 2 Cr =(6.90±0.27)×10 4 M -2 s -1和k 2 BPO =(3.32±0.28)×10 5 M -2 s -1在0.10 M HClO 4中。速率常数k 2 Cr包含与[H + ]独立和[H + ]催化的路径相对应的项。在提出的机制中,最初形成的Cr aq(BPO)2+参与Cr aq的平行氧化2+和降低BPO。后一反应为Cr(
Enzymatic Synthesis of Optically Active a-Hydroxybenzylpyridines
Synthesis of optically active alpha-hydroxybenzylpyridines by asymmetric reduction of benzoylpyridines and benzoylpyridine N-oxides with baker's yeast, and enantioselective esterification of racemic alpha-hydroxybenzylpyridines by use of lipase PS have been described.