Palladium-catalyzed cross-coupling of aziridinylmetal species, generated by sulfinyl-magnesium exchange, with aryl bromides: reaction optimization, scope, and kinetic investigations.
Palladium-catalyzed cross-coupling of aziridinylmetal species, generated by sulfinyl-magnesium exchange, with aryl bromides: reaction optimization, scope, and kinetic investigations.
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钯催化的氮丙啶基金属物质（通过亚磺酰基镁交换产生）与芳基溴的交叉偶联：反应优化、范围和动力学研究。
作者：
M. Hughes;Tom Boultwood;Gianfranco Zeppetelli;J. Bull
通过钯催化完整叠氮嘧啶的交叉偶联，获得了一系列新的、高取代的N-PMP叠氮嘧啶。交叉偶联采用芳基溴和叔有机金属氮化吡啶，由亚砜基氮化吡啶经亚砜基-镁交换和氯化锌转金属制得氮化吡啶锌。利用各种富电子和贫电子的芳基溴，得到具有单一非对映异构体的功能化叠氮产物，并在反应中心保留构型。反应动力学评价表明，在氮吡啶类和芳基溴中均为零级反应。这表明，反应速率的决定步骤是同时含有氮吡啶和芳基的钯（II）的还原性消除，以形成受阻的C-C键。中间体aziridinylzinc经历了一个渐进的背景降解过程，导致产量停滞不前，并且在邻取代芳基的底物中产量降低，因为邻取代芳基由于额外的空间要求而反应性较差。
A series of novel, highly substituted N-PMP aziridines have been accessed in high yields by palladium-catalyzed cross-coupling of intact aziridines. The cross-coupling employed aryl bromides and tertiary organometallic aziridines, generated from sulfinylaziridines by sulfinyl-magnesium exchange and transmetalation to the aziridinylzinc with zinc chloride. A wide range of electron-rich and electron-poor aryl bromides were utilized to afford the functionalized aziridine products as single diastereoisomers with retention of configuration at the reacting center. Assessment of the reaction kinetics showed zero-order in both the aziridine species and the aryl bromide. This indicated that the rate-determining step was reductive elimination from the palladium(II) species bearing both the aziridine and aryl groups to form the hindered C-C bond. The intermediate aziridinylzinc species underwent a progressive, background degradation that led to a plateau in yield and afforded reduced yields in substrates with ortho-substituted aryl groups, which are less reactive due to the additional steric demands.
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