Radical Addition Approach to Asymmetric Amine Synthesis: Design, Implementation, and Comparison of Chiral <i>N</i>-Acylhydrazones
作者:Gregory K. Friestad、Cristian Draghici、Mustapha Soukri、Jun Qin
DOI:10.1021/jo050756m
日期:2005.8.1
construction approach to chiral amines. Here, complete details of the first radical additions to chiral N-acylhydrazones as an approach to asymmetric amine synthesis are disclosed. Novel N-acylhydrazones were designed as chiral CN radical acceptors with Lewis acid activation, restriction of conformational mobility, and commercial availability of precursors. Amination of 4-alkyl-2-oxazolidinones with O-(m
Mn-Mediated Coupling of Alkyl Iodides and Chiral <i>N</i>-Acylhydrazones: Optimization, Scope, and Evidence for a Radical Mechanism
作者:Gregory K. Friestad、Jean-Charles Marié、Suh、Jun Qin
DOI:10.1021/jo061158q
日期:2006.9.1
of the use of photolysis with manganese carbonyl to mediate stereoselectiveintermolecularradicaladdition to N-acylhydrazones. Photolysis (300 nm) of alkyl halides and hydrazones in the presence of Mn2(CO)10 and InCl3 as a Lewis acid led to reductive radicaladdition; diastereomer ratios ranged from 93:7 to 98:2 at ca. 35 °C. The reaction tolerates additional functionality in either reactant, enabling
立体选择性自由基加成物具有优异的潜力,可用于直接不对称胺合成的温和,非碱性碳-碳键结构。具有无环立体控制的向C N键的有效分子间自由基加成以前主要限于仲和叔自由基,这从合成应用的角度来看是一个严重的局限。在这里,我们提供了使用光解与羰基锰介导N-酰基hydr的立体选择性分子间自由基加成的完整细节。Mn 2(CO)10和InCl 3存在下卤代烷和的光解(300 nm)由于路易斯酸导致还原性自由基的添加;非对映体比在约93∶7至98∶2的范围内。35°C。该反应可耐受任一反应物的附加功能,从而可以进行后续的转化,如有效的不对称甜氨酸合成所示。比较了一系列在恶唑烷酮助剂上带有不同取代基的;始终如一的高非对映控制表明,取代基的身份对非对映选择性几乎没有实际影响。进一步的机械控制实验证实了自由基的中介性,并表明独立制备的烷基或酰基锰五羰基化合物没有有效地添加到氮中-酰基hydr在热或光解(300 n
Strecker Reactions of Chiral N-Acylhydrazones
作者:Gregory K. Friestad、Hui Ding
DOI:10.3987/com-06-s(w)3
日期:——
of a method for addition of trimethylsilylcyanide to chiral oxazolidinone-derived N-acylhydrazones is described. The diastereoselectivity was found to be highly dependent on the substituent of the oxazolidinone moiety; 4-phenyl-2-oxazolidinone achieved much higher stereocontrol than four other oxazolidinones screened. The reaction gives modest selectivity with aliphatic hydrazones and excellent selectivity