The potential of β‐alkoxy α‐keto amides as pronucleophiles in the enantioselective Mannich type reaction with p‐nosyl imines is presented. The proper combination of β‐alkoxy α‐keto amides and a squaramide‐based Brønsted basecatalyst produced highly enantioenriched Mannich adducts, which may be transformed into functionalized amino diols.
Formation of N-sulfonyl imines from iminoiodinanes by iodine-promoted, N-centered radical sulfonamidation of aldehydes
作者:Megan D. Hopkins、Kristina A. Scott、Brettany C. DeMier、Heather R. Morgan、Jesse A. Macgruder、Angus A. Lamar
DOI:10.1039/c7ob02120h
日期:——
A mild and operationally convenient formation of synthetically valuable N-sulfonyl iminesfrom a range of aryl aldehydes by reaction with iminoiodinanes (PhINZ) and I2 has been developed. According to mechanistic experiments described within, the reaction is speculated to proceed through an unconventional light-promoted, N-centered radical (NCR) pathway involving a N,N-diiodosulfonamide reactive species
作者:Sobia Tabassum、Oksana Sereda、Peddiahgari Vasu Govardhana Reddy、René Wilhelm
DOI:10.1039/b908899g
日期:——
KHMDS and KOtBu are well established as strong, hindered, non-nucleophilic Brønsted bases. However, in the present work these bases are applied as highly active Lewis base catalysts for the formal [2+2] cycloaddition of ketenes with aldehydes and imines.
Hydroxyproline-Derived Pseudoenantiomeric [2.2.1] Bicyclic Phosphines: Asymmetric Synthesis of (+)- and (−)-Pyrrolines
作者:Christopher E. Henry、Qihai Xu、Yi Chiao Fan、Tioga J. Martin、Lee Belding、Travis Dudding、Ohyun Kwon
DOI:10.1021/ja505592h
日期:2014.8.27
We have prepared two new diastereoisomeric 2-aza-5-phosphabicyclo[2.2.1]heptanes from naturally occurring trans-4-hydroxy-l-proline in six chemical operations. These syntheses are concise and highly efficient, with straightforward purification. When we used these chiral phosphines as catalysts for reactions of γ-substituted allenoates with imines, we obtained enantiomerically enriched pyrrolines in
Catalytic Enantioselective Synthesis of Guvacine Derivatives through [4 + 2] Annulations of Imines with α-Methylallenoates
作者:Qihai Xu、Nathan J. Dupper、Andrew J. Smaligo、Yi Chiao Fan、Lingchao Cai、Zhiming Wang、Adam D. Langenbacher、Jau-Nian Chen、Ohyun Kwon
DOI:10.1021/acs.orglett.8b02489
日期:2018.10.5
These HypPhos catalysts were assembled from trans-4-hydroxyproline, with the modular nature of the synthesis allowing variations of the exocyclic P and N substituents. Among them, exo-(p-anisyl)-HypPhos was most efficacious for [4 + 2] annulations between ethyl α-methylallenoate and imines. Through this method, (R)-aplexone was identified as being responsible for the decrease in the cellular levels
P-手性[2.2.1]双环膦(HypPhos催化剂)已应用于α-烷基联烯酸酯和亚胺之间的反应,生产鳄梨毒肽衍生物。这些 HypPhos 催化剂由反式-4-羟基脯氨酸组装而成,合成的模块化性质允许环外 P 和 N 取代基的变化。其中, exo -(对茴香基)-HypPhos 对于 α-甲基联烯酸乙酯和亚胺之间的 [4 + 2] 成环最有效。通过这种方法,( R )-aplexone 被确定为细胞胆固醇水平降低的原因。