A facile and effective synthesis of 2-azetidinones via phosphonitrilic chloride
作者:Maaroof Zarei
DOI:10.1016/j.tet.2013.05.121
日期:2013.8
The Staudinger reaction of imines to β-lactams was successfully achieved with substituted acetic acid and phosphonitrilicchloride in one-pot under mild conditions. Several types of β-lactams, especially 3-electron-withdrawing group β-lactams, can be synthesized by this versatile and efficient method in good to excellent yields. This method is simple, clean, and the by-products were removed by simple
protection of threaded functions by the macrocycle, in this case promoting an unusual and disfavored 4-exo-trig ringclosure. Kinetic and synthetic studies allowed us to delineate an advantageous approach toward β-lactams based on a two-step, one-pot protocol: an intramolecular ringclosure followed by a thermally induced dethreading step. The advantages of carrying out this cyclization in the confined
Cobalt‐Catalyzed α‐Arylation of Substituted α‐Bromo α‐Fluoro β‐Lactams with Diaryl Zinc Reagents: Generalization to Functionalized Bromo Derivatives
作者:Mélanie M. Lorion、Vanessa Koch、Martin Nieger、Hi‐Yung Chen、Aiwen Lei、Stefan Bräse、Janine Cossy
DOI:10.1002/chem.202001721
日期:2020.10.15
A cobalt‐catalyzed cross‐coupling of α‐bromo α‐fluoro β‐lactams with diarylzinc or diallylzinc reagents is herein disclosed. The protocol proved to be general, chemoselective and operationally simple allowing the C4 functionalization of β‐lactams. The substrate scope was expanded to α‐bromo lactams and amides, α‐bromo lactones and esters as well as N‐ and O‐containing heterocycles.
The first example of a base‐metal‐catalyzed homogeneous hydrogenative coupling of nitriles and amines to selectively form secondary cross‐imines is reported. The reaction is catalyzed under mild conditions by a well‐defined (iPr‐PNP)Fe(H)Br(CO) pincer pre‐catalyst and catalytic tBuOK.
One-Pot Sequence Synthesis of Azetidin-2-One Using Diethyl Chlorophosphate
作者:Maaroof Zarei
DOI:10.3184/174751912x13282660033937
日期:2012.2
A simple and convenient synthesis of 2-azetidinone derivatives from the reaction of a pre-mixture of amines and aldehydes with carboxylic acids in the presence of diethyl chlorophosphate by [2+2] cycloaddition reaction is described. Separation and purification of imines as intermediates were not required. The methodology is convenient and good to excellent yields of products were obtained with simple