Substrate scope and stereocontrol in the Rh(II)-catalysed oxyamination of allylic carbamates
摘要:
Application of a modified Du Bois protocol for rhodium-stabilised nitrenoid generation to a variety of allylic carbamates results in 4-acetoxymethyl-1,3-oxazolidin-2-one derivatives with moderate to high levels of stereocontrol. (C) 2014 Elsevier Ltd. All rights reserved.
Tethered Aminohydroxylation: Dramatic Improvements to the Process
作者:Timothy J. Donohoe、Carole J. R. Bataille、William Gattrell、Johannes Kloesges、Emilie Rossignol
DOI:10.1021/ol070430v
日期:2007.4.1
[reaction: see text] Changing the identity of the N leaving group on a hydroxylamine-based reoxidant gives a dramatic improvement to the tetheredaminohydroxylationreaction. Using OCOC6F5 as a leaving group means that only 1 mol % of osmium is required and yields as high as 98% can be obtained. Acyclic homoallylic alcohols were substrates considered too unreactive for effective use in the tethered
The reaction of dienyl carbamates with PhI(OR)2 in the presence of rhodium catalysts affords vinyl aziridines which are in situ regio- and stereoselectively opened to afford oxyamination products resulting from a selective S(N)2 (Rh2(OAc)4/PhI(OPiv)2) or S(N)2' (Rh2(OPiv)4/PhI(OAc)2) opening. The scope and limitations of this tandem process are described.
Enantioselective Synthesis of Aminodiols by Sequential Rhodium‐Catalysed Oxyamination/Kinetic Resolution: Expanding the Substrate Scope of Amidine‐Based Catalysis
Regio‐ and stereoselective oxyamination of dienes through a tandem rhodium‐catalysed aziridination–nucleophilic opening affords racemic oxazolidinone derivatives, which undergo a kinetic resolution acylation process with amidine‐based catalysts (ABCs) to achieve s values of up to 117. This protocol was applied to the enantioselective synthesis of sphingosine.
A general protocol for the enantioselectivesynthesis of 3-heterosubstituted-2-amino-1-ols was developed based on metal- free intramolecular regio- and stereoselective diene aziridination and regioselective opening. Kinetic resolution of the resulting (1'-NR1 R2 and 1'-SR)-4-oxazolidinones was performed using ABCs organocatalysts, expanding the application of this methodology.