diastereoselective synthesis of syn-α-bromo-α-fluoro-β-lactams was achieved using the diethylzinc-mediated Reformatsky-type reaction of ethyl dibromofluoroacetate with imines. The reaction led to diastereomerically pure β-lactams in good to moderate yields (up to 78% yield) with only small amounts of aziridine derivatives. Noncyclized 3-amino-2-bromo-2-fluoro carboxylic esters, usual Reformatsky adducts, were
Diethylzinc-Mediated Addition of 2,2-Dibromo-2-fluoroacetamides to Carbonyl Compounds: Synthesis of α-Bromo-α-fluoro-β-hydroxy Amides and/or (<i>Z</i>)-Fluorovinyl Amides
We describe straightforward routes either to α-bromo-α-fluoro-β-hydroxy amides or to (Z)-α-fluoroacrylamides starting from aldehydes, ketones or imine and 2,2-dibromo-2-fluoroacetamides. Depending on the nature of the amide, these diethylzinc-mediated additions to aldehydes, ketones or imine afford selective access either to bromofluorohydrins or to (Z)-α-fluoroacrylamides. The corresponding products
我们描述了从醛、酮或亚胺和 2,2-二溴-2-氟乙酰胺开始的 α-溴-α-氟-β-羟基酰胺或 (Z)-α-氟丙烯酰胺的直接路线。根据酰胺的性质,这些二乙基锌介导的与醛、酮或亚胺的加成提供了对溴氟醇或 (Z)-α-氟丙烯酰胺的选择性访问。以中等至非常好的产率获得了相应的产品,两种产品的构型均通过 X 射线分析得到证实。
Ni-catalyzed α-arylation of secondary α-bromo-α-fluoro-β-lactam: cross-coupling of a secondary fluorine-containing electrophile
A highly diastereoselective cross-coupling reaction of an α-bromo-α-fluoro-β-lactam with a wide range of aryl Grignard reagents was catalyzed by Ni/bis(oxazoline) in yields of up to 98%. The product was obtained diastereoselectively as an anti-isomer. This is the first successful α-arylation of an α-fluoro-β-lactam to produce diverse α-aryl-α-fluoro-β-lactams.
Ni /双(恶唑啉)催化α-溴-α-氟-β-内酰胺与多种芳基格氏试剂的高度非对映选择性交叉偶联反应,收率高达98%。非对映选择性地获得该产物作为反异构体。这是α-氟-β-内酰胺成功生产出多种α-芳基-α-氟-β-内酰胺的第一个成功的α-芳基化反应。