MECHANISM OF OXYGEN ATOM TRANSFER FROM OXAZIRIDINE TO A LITHIUM ENOLATE - A THEORETICAL-STUDY
MECHANISM OF OXYGEN ATOM TRANSFER FROM OXAZIRIDINE TO A LITHIUM ENOLATE - A THEORETICAL-STUDY
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DOI：
10.1021/jo00028a039
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发表时间：
1992-01-17
影响因子：
3.6
通讯作者：
DAVIS, FA
中科院分区：
文献类型：
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作者：
BACH, RD;ANDRES, JL;DAVIS, FA
使用对映体N-磺酰氧氮杂氮杂环丙烷的不对称烯醇氧化法在合成对映体富集型α-羟基羰基化合物方面非常成功。在HF/6-31+G*//HF/4-31+G水平上进行了分子轨道计算，阐明了氧原子转移过渡态的结构和电子特征。乙醛的烯酸锂的氧化是由S(N)2沿着母体恶嗪的O-N键对烯酸锂的β-碳的攻击进行的。在过渡态，锂离子同时配位于烯醇氧原子和恶杂环丙烷氧原子。模型研究表明，磺酰氧原子也与金属阳离子结合，影响生成的α-羟基羰基化合物的立体选择性。
The asymmetric enolate oxidation protocol employing enantiopure N-sulfonyloxaziridines is highly successful in the synthesis of enantiomerically enriched alpha-hydroxy carbonyl compounds. Molecular orbital calculations at the HF/6-31 + G*//HF/4-31 + G level have been used on a model system to elucidate the structural and electronic features of the transition state for oxygen atom transfer. Oxidation of the lithium enolate of acetaldehyde proceeds by S(N)2 attack of the beta-carbon on the enolate along the O-N bond of the parent oxaziridine. In the transition state the lithium cation is coordinated to both the enolate and the oxaziridine oxygen atoms. Model studies suggest that the sulfonyl oxygen atom is also bound to the metal cation, influencing the stereoselectivity of the resulting alpha-hydroxy carbonyl compound.