Online article for Non-subscribers

Pay per view

Heterocycles has a pay-per-view service for Non-subscribers.
You will be able to directly purchase the full text article through PayPal.
Your purchased Paper can be downloaded after the payment is completed.
An e-mail will be sent the URL to download the paper.
If you have any questions, please contact: purchase@heterocycles.com

Price: ¥ 4,400 (Yen only)
Period: This Article can be accessed for 7 days.

Paper | Regular issue | Vol 27, No. 4, 1988, pp.955-959
Published online, 1st January, 1970
DOI: 10.3987/COM-87-4447
Remote Induction of the Condensation of p-Nitrobenzaldehyde on the Methylene Group of 5-Hydroxy-2-coumaranone

Michel Barbier*

*Institut des Chimie des Substances Naturelles, C.N.R.S., 1 avenue de la Terrasse, Bat. 27, 91198 Gif-sur-Yvette Cedex, France

Abstract

(Z)-5-Hydroxy-3-(p-nitrobenzylidene)-2-coumaranone ((Z)-p-nitromarginalin) is obtained in 92% yield by reaction of p-nitrobenzaldehyde with 5-hydrony-2-coumaranone. The same condensation carried out with 2-coumaranone gives a mixture of (Z)- and (E)-p-nitrobenzylidene-2-caumaranones (72% yield) in a 2:1 ratio. In a discussion taking also into account previous results in the series, it is concluded that the 5-hydroxyl group exerts a remote induction in the orientation of the intermediate secondary alcohol, stabilized through chelation with the lactone carbonyl group. Such a long distance effect is in agreement with the requirements of the Cram’s rule, leading in this particular case to a high stereoselectivity in the final dehydrated ene-lactone.