The Thermal Benzoxazinone-Benzoxazole Conversion, a Reexecution of a Mass Spectrometric Decay by Thermolysis
作者:Werner Reichen
DOI:10.1002/hlca.19770600121
日期:1977.1.26
The base peak in the mass spectrum of several 1,4,2-benzoxazinone derivatives 1a–f (cf. Scheme 1 and the Table) suggests a clean carbon monoxide elimination leading to benzoxazole radical cations 2a–f. This benzoxazinone-benzoxazoleconversion can be reproduced quantitatively by flash vacuum thermolysis.
Addition of catechol to methyl propiolate or ethyl phenylpropiolate in the presence of Ph3P leads to methyl 2-(1,3-benzodioxol-2-yl)acetate or 3-(1-phenylmethylidene)-1,4-benzodioxin-2-one. 2-Aminophenols react with alkyl propiolates in the presence of Ph3P to produce a nearly 1:1 mixture of 3-methyl-2H-1,4-benzoxazin-2-one derivatives and methyl (E)-3-(2-aminophenoxy)-2-propenoates.
Asymmetric hydrogenation of 3-methylbenz[b][1,4]oxazin-2-ones catalyzed by iridium complexes with phosphite-type ligands
作者:A. E. Lyubimov、D. B. Ozolin、V. A. Davankov
DOI:10.1007/s11172-016-1384-1
日期:2016.3
The chiral amidophosphite ligand in the iridium-catalyzed hydrogenation of 3-methylbenz[b][1,4]oxazin-2-ones in ethanol provides higher conversion and enantioselectivity than the phosphite ligand.
<i>N</i>
‐Heterocyclic Carbene Catalyzed [3+2] Cycloaddition of Enals with
<i>β,γ</i>
‐Unsaturated
<i>α</i>
‐Ketimino Esters for the Synthesis of Multisubstituted Cyclopentanone
A convenient strategy of N‐heterocycliccarbene catalyzed [3+2] cycloaddition of enals with β,γ‐unsaturated α‐ketimino esters is developed. This effective protocol features mild reaction conditions and broad substrate scope, which enables the rapid assembly of various benzoxazinone derived cyclopentanone scaffolds in good to high yields with excellent diastereoselectivities.