Base-promoted reaction of O-sulfonylated hydroxamic acids with nucleophiles. A new method for the synthesis of .alpha.-substituted amides
摘要:
Treatment of a series of hydroxamic acids 2 with mesyl chloride in the presence of 2 equiv of triethylamine at 0-degrees-C gives 2-chloroamides 3 in good yields. Use of a single equivalent of triethylamine gives the (N-mesyl-oxy)amides 1, which are versatile synthetic intermediates as they can be readily converted to 2-bromoamides 4 with lithium bromide and triethylamine and to 2-hydroxyamides 5 with triethylamine in aqueous acetonitrile.
Enantioselective synthesis of β-hydroxy-α-methyl carbonyl compounds by aldol reaction
作者:Akira Ando、Takayuki Shioiri
DOI:10.1016/s0040-4020(01)81078-4
日期:——
The enantioselective aldolreactions of ketone lithium enolates with aldehydes mediated chiral lithium amides were extensively investigated. The chiral amino ethers 4a–4l and diamines 16a,b were prepared from α-amino acids. The reaction conditions and the substituent effects of chiral lithium amides were examined using 4a–4l and 16a,b in the aldolreaction of lithium enolate of 2,2-dimethyl-3-pentanone
Synthesis of α-Methylene-β-lactams Enabled by Base-Promoted Intramolecular 1,2-Addition of <i>N</i>-Propiolamide and C–C Bond Migrating Cleavage of Aziridine
mmol scaled synthesis of α-methylene-β-lactams and synthetic applications of α-methylene-β-lactams are also reached. In the process, it is believed that an intramolecular 1,2-addition of N-propiolamide and sequential C–Cbond migrating cleavage are involved.
据报道,N-丙酰胺和2-溴乙酸的正式α-加成以高收率合成了α-亚甲基-β-内酰胺。在以K 2 CO 3为碱和KI为添加剂的情况下,转化过程顺利进行。观察到极好的反应范围。还实现了2 mmol规模的α-亚甲基-β-内酰胺的合成和α-亚甲基-β-内酰胺的合成应用。在此过程中,据信涉及分子内N-丙醇酰胺的1,2-加成和连续的C-C键迁移裂解。
Origins of Regioselectivity in the Reactions of α-Lactams with Nucleophiles. Two Distinct Acid-Catalyzed Pathways Involving O- and N-Protonation
作者:Robert V. Hoffman、Zhiqiang Zhao、Abran Costales、David Clarke
DOI:10.1021/jo020246h
日期:2002.7.1
nucleophilic attack at the C-3 carbon and yields C-3 products. The mechanism thus developed is very useful for understanding the changes in rates and product distributions in the reactions of sterically stabilized alpha-lactams with nucleophiles. It can also be extrapolated to other alpha-lactams so that a more coherent picture of alpha-lactam reactivity can be developed.
DFT calculations and an experimental study of fluorination of 2-bromoamides with AgF and trifluoromethylthiolation with AgSCF3 were performed in order to elucidate their reaction mechanisms, which provide a robust synthetic method for chiral 2-fluoro- and 2-SCF3 amide compounds.