example of oxyamination of azlactones with oxaziridines was realized using a chiral bisguanidinium salt. Efficient catalytic asymmetric oxyamination and kinetic resolution of oxaziridines occurred simultaneously. Various chiral oxazolin-4-one derivatives with potential biological activity were obtained (up to 92% ee). Meanwhile, a series of optically pure oxaziridines were recovered with up to 99% ee and
A highly enantioselective synthesis of 3,4-diaminochroman-2-ones has been realized via the domino reaction of o-hydroxy aromatic aldimines and azlactones. Notably, a cis-product was obtained as the major product by the use of guanidine 2a whereas a trans-product was the major product with bisguanidium salt 3•HBArF4. In two cases, various substituted 3,4-dihydrocoumarins were obtained with high yields
通过邻羟基芳族醛亚胺和a内酯的多米诺反应,已经实现了对3,4-二氨基苯并二氢吡喃-2-酮的高度对映选择性的合成。值得注意的是,通过使用胍2a获得了顺式产物作为主要产物,而反式产物是双胍盐3•HBAr F 4的主要产物。在两种情况下,以高收率(高达99%),出色的对映选择性(高达99%ee)和非对映选择性(高达> 99:1顺式:反式和98:2 )获得了各种取代的3,4-二氢香豆素。反式:顺式,分别)在温和的反应条件下。
[3 + 2] Cycloaddition of Oxazol-5-(4<i>H</i>)-ones with Nitrones for Diastereoselective Synthesis of Isoxazolidin-5-ones
In the presence of TMSCl, the [3 + 2] cycloaddition of oxazol-5-(4H)-ones with nitrones proceeded smoothly and furnished the desired isoxazolidin-5-ones with high diastereoselectivities in reasonable chemical yields. The chemical structure of the title compounds was firmly confirmed by X-ray single-crystal structure analysis.
In the presence of DIPEA (diisopropylethylamine), a formal [3+2] cycloaddition reaction between diazooxindoles and oxazol‐5‐(4H)‐ones takes place easily to give new 3‐(1H‐1,2,4‐triazol‐1‐yl)indolin‐2‐ones in 61–98 % yield. The structure of the target molecules was confirmed by single‐crystal X‐ray structure analysis.
在存在DIPEA(二异丙基乙胺)的情况下,重氮恶唑与恶唑-5-(4 H)-酮之间的[3 + 2]环加成反应很容易发生,从而生成新的3-(1 H -1、1,2,4-三唑‐1-yl)indolin-2-ones的产率为61–98%。通过单晶X射线结构分析确认了目标分子的结构。
Organocatalytic Enantioselective Conjugate Addition of Azlactones to Enolizable Linear and Cyclic Enones
作者:Chao-Ming Wang、Jun-An Xiao、Jing Wang、Sha-Sha Wang、Zhao-Xu Deng、Hua Yang
DOI:10.1021/acs.joc.6b01356
日期:2016.9.2
Highly diastereo- and enantioselective conjugateadditions of azlactones to enolizable cyclic and linear enones were conducted by employing proline aryl sulfonamide as the organocatalyst in trifluorotoluene. The conjugate adducts bearing contiguous quaternary and tertiarystereocenters were obtained in moderate to good yields with excellent diastereoselectivities and moderate to good enantioselectivities