Oxygen Insertion of o-Quinone under Catalytic Hydrogenation Conditions
摘要:
An oxygen-insertion reaction that transforms an o-quinone and a conjugated alpha-diketone substrate Into an anhydride product or derivative under catalytic hydrogenation conditions is reported. The experiments and computations indicate that the oxygen insertion proceeds via a radical mechanism mediated by an acetoxyl radical.
Total Synthesis of (±)‐Phyllantidine: Development and Mechanistic Evaluation of a Ring Expansion for Installation of Embedded Nitrogen‐Oxygen Bonds
作者:Kyle M. Lambert、Joshua B. Cox、Lin Liu、Amy C. Jackson、Sam Yruegas、Kenneth B. Wiberg、John L. Wood
DOI:10.1002/anie.202003829
日期:2020.6.8
The development of a concise total synthesis of (±)‐phyllantidine (1 ), a member of the securinega family of alkaloids containing an unusual oxazabicyclo[3.3.1]nonane core, is described. The synthesisemploys a unique synthetic strategy featuring the ring expansion of a substituted cyclopentanone to a cyclic hydroxamic acid as a key step that allows facile installation of the embedded nitrogen‐oxygen
A novel Zn(OAc)2-catalyzed three-component tandem cyclization reaction of isocyanides, α-diazoketones and anhydrides has been developed. The reaction demonstrates the wide scope of substrates and provides a novel and efficient strategy for the synthesis of polysubstituted maleimides from readily available substrates in a single step.
Synthesis of 5-Acetyloxazoles and 1,2-Diketones from β-Alkoxy-β-ketoenamides and Their Subsequent Transformations
作者:Tilman Lechel、Markus Gerhard、Daniel Trawny、Boris Brusilowskij、Luise Schefzig、Reinhold Zimmer、Jürgen P. Rabe、Dieter Lentz、Christoph A. Schalley、Hans-Ulrich Reissig
DOI:10.1002/chem.201100382
日期:2011.6.27
cyclized to 5‐acetyloxazole derivatives. The synthesis is very flexible with respect to the substitution pattern at C‐2 and C‐4 of the oxazole core. A mechanistic suggestion for the oxazole formation is presented on the basis of 18O‐labeled compounds and their mass spectrometric analysis. In several cases, 1,2‐diketones are formed as side products or even as major components. The acetyl moiety at C‐5 of the
Isocyanide based multicomponent reactions of oxazolidines and related systems
作者:Robert W. Waller、Louis J. Diorazio、Brian A. Taylor、William B. Motherwell、Tom D. Sheppard
DOI:10.1016/j.tet.2010.05.083
日期:2010.8
aldehydes/ketones, isocyanides and carboxylic acids. The reaction of oxazolidines without a nitrogen substituent was found to give either the expected Ugi products or the N-acyloxyethylamino acid amides depending on the choice of reaction conditions. Optimised reaction conditions were also developed for the ring-expansion of oxazolidines to morpholin-2-ones via reaction with an isocyanide followed by hydrolysis
The protection of carboxyl groups by esterification has been the most common method in macroscale and microscale chemistries. The esterification is usually conducted under anhydrous conditions; however, in biological chemistry and related fields, the reaction is of major concern in aqueous environments. Immediate esterification of the carboxyl in aqueous alcoholic media driven by an alkyl chloroformate