Acid-catalyzed cyclization reactions. IX. Formation of oxazolinium and thiazolinium cation from N-allyl and substituted N-allylamides, -urethans, -ureas, and -thioureas
Asymmetric catalysis based on chiral phospholanes and hydroxyl phospholanes
申请人:The Penn State Research Foundation
公开号:US06337406B1
公开(公告)日:2002-01-08
Chiral phosphine ligands derived from chiral natural products including D-mannitol and tartaric acid. The ligands contain one or more 5-membered phospholane rings with multiple chiral centers, and provide high stereoselectivity in asymmetric reactions.
developed via the oxidative umpolung of bromide using alkali metal bromide and inorganic oxidant to provide the corresponding cyclization products in high yields. In particular, the use of AcOEt, the solvent of choice for green sustainable reactions, led to the high reactivities of the present reactions. This methodology is highly recommended for green sustainable chemistry because it uses stable and non-hazardous
Enantioselective Rh-Catalyzed Anti-Markovnikov Hydroformylation of 1,1-Disubstituted Allylic Alcohols and Amines: An Efficient Route to Chiral Lactones and Lactams
Rh-catalyzed highly enantioselective anti-Markovnikov hydroformylation of 1,1-disubstituted allylic alcohols and amines has been achieved. By using a chiral hybrid phosphorus ligand, a series of challenging 1,1-disubstituted allylic alcohols and amines were transformed to valuable chiral lactones and lactams with good yields and high enantioselectivities (up to 90% yield and 93% enantiomeric excess
已经实现了Rh催化的1,1-二取代的烯丙基醇和胺的高对映选择性的反马尔科夫尼科夫加氢甲酰基化。通过使用手性杂化磷配体,将一系列具有挑战性的1,1-二取代的烯丙醇和胺转化为有价值的手性内酯和内酰胺,具有良好的收率和高对映选择性(高达90%的收率和93%的对映体过量(ee))在非常温和的反应条件下(50°C,CO / H 2 = 2.5 / 2.5 bar)。此外,还实现了克级反应和多种合成转化,证明了该方法的广泛合成效用。
Improved Synthetic Method for 5-[(Phenylthio)methyl]oxazoline Derivatives: Electrophilic Cyclization of Allylic Amide Using a Brønsted Acid and Tetrabutylammonium Chloride under Mild Conditions
作者:Yoshihiro Nagao、Kou Hiroya
DOI:10.1055/s-0039-1690836
日期:2020.5
using electrophilic cyclization of allylic amide is a simple and powerful method. However, cyclization involving arylsulfenylation requires harsh reaction conditions. We found that the reaction proceeds under mild heating conditions with the combination of a Bronsted acid and tetrabutylammonium chloride. This method enabled the synthesis of 5-[(arylsulfenyl)methyl]oxazoline derivatives under mild conditions
DAST-mediated ring-opening of cyclopropyl silyl ethers in nitriles: facile synthesis of allylic amides <i>via</i> a Ritter-type process
作者:Masayuki Kirihara、Riho Nakamura、Kana Nakakura、Kazuki Tujimoto、Mohamed S. H. Salem、Takeyuki Suzuki、Shinobu Takizawa
DOI:10.1039/d2ob00940d
日期:——
A diethylaminosulfur trifluoride (DAST)-mediated ring-opening reaction of cyclopropyl silyl ethers in nitriles produced allylic amides in moderate to good yields (up to 87%). Time course studies using ReactIR and O-isotopic labeling mechanistic studies suggested that the present reaction occurs via a Ritter-type process, leading to the formation of allylic amides.
二乙氨基三氟化硫 (DAST) 介导的环丙基甲硅烷基醚在腈中的开环反应以中等至良好的产率(高达 87%)产生烯丙基酰胺。使用 ReactIR 和 O 同位素标记机理研究的时间过程研究表明,本反应通过Ritter 型过程发生,导致烯丙基酰胺的形成。