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.
Shridhar,D.R. et al., Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 1979, vol. 18, p. 251 - 253
作者:Shridhar,D.R. et al.
DOI:——
日期:——
Organocatalyzed asymmetric cascade Mannich/cyclization of 3-isothiocyanato oxindoles with cyclic ketimines for the synthesis of polycyclic spiro-thioimidazolidine-oxindoles
The first diastereo- and enantioselective cascade Mannich/cyclization reaction of 3-isothiocyanato oxindoles with cyclic ketimines has been successfully developed. By using chiral bifunctional organocatalysts, a range of structurally diverse chiral polycyclic spiro-thioimidazolidine-oxindoles, bearing two contiguous tetrasubstituted stereocenters, could be obtained in excellent yields (up to 99%) with good diastereo- and enantioselectivities (up to >20:1 dr and 94.5:5.5 er) under mild reaction conditions. (C) 2020 Elsevier Ltd. All rights reserved.
SHRIDHAR D. R.; LAL B.; VAIDYA N. K.; PHOPALE K. K.; TRIPATHI H. N., INDIAN J. CHEM., 1979, B 18, NO 3, 251-253
作者:SHRIDHAR D. R.、 LAL B.、 VAIDYA N. K.、 PHOPALE K. K.、 TRIPATHI H. N.