cis/trans-Isochromanones. DMAP induced cycloaddition of homophthalic anhydride and aldehydes
摘要:
Homophthalic anhydride (1) reacts with wide variety of aromatic aldehydes, in the presence of chloroform and DMAP (N,N-dimethyl-4-amino-pyridine) at room temperature, to give in high yields cis- and trans-1-oxo-isochroman-4-carboxylic acids. Under these conditions, the trans-isomer is predominant and formation of Perkin-type products was not observed in contrast to the reaction carried out in the presence of pyridine. The unexpected trans-6-oxo-11-thiophen-2-yl-11,12-dihydro-6H-dibenzo[c,h]chromene-12-carboxylic acid methyl ester (8) was isolated when the reaction between 1 and thiophene-2-carbaldehyde was carried out in pyridine. (C) 2004 Elsevier Ltd. All rights reserved.
Catalytic Asymmetric Cycloadditions between Aldehydes and Enolizable Anhydrides: <i>cis</i>-Selective Dihydroisocoumarin Formation
作者:Maria Luisa Aiello、Umar Farid、Cristina Trujillo、Brendan Twamley、Stephen J. Connon
DOI:10.1021/acs.joc.8b02332
日期:2018.12.21
In the presence of a trityl-substituted cinchona alkaloid-based catalyst, homophthalic, aryl succinic, and glutaconic anhydride derivatives reacted with aromatic and aliphatic aldehydes to produce cis-lactones in up to 90:10 dr and 99% ee. A DFT study has shown how the catalyst is uniquely able to bring about the opposite sense of diastereocontrol to that usually observed.
cis/trans-Isochromanones. DMAP induced cycloaddition of homophthalic anhydride and aldehydes
作者:Milen G Bogdanov、Mariana D Palamareva
DOI:10.1016/j.tet.2004.01.040
日期:2004.3
Homophthalic anhydride (1) reacts with wide variety of aromatic aldehydes, in the presence of chloroform and DMAP (N,N-dimethyl-4-amino-pyridine) at room temperature, to give in high yields cis- and trans-1-oxo-isochroman-4-carboxylic acids. Under these conditions, the trans-isomer is predominant and formation of Perkin-type products was not observed in contrast to the reaction carried out in the presence of pyridine. The unexpected trans-6-oxo-11-thiophen-2-yl-11,12-dihydro-6H-dibenzo[c,h]chromene-12-carboxylic acid methyl ester (8) was isolated when the reaction between 1 and thiophene-2-carbaldehyde was carried out in pyridine. (C) 2004 Elsevier Ltd. All rights reserved.