Seven-Membered Ring Chelates as a Tool for Stereocontrol in Intramolecular Diels-Alder Reactions: Application to a Short Synthesis of α-Eudesmol
- 1 January 1991
- journal article
- letter
- Published by Georg Thieme Verlag KG in Synlett
- Vol. 1991 (12) , 854-856
- https://doi.org/10.1055/s-1991-20900
Abstract
5-Methoxycarbonyl-1,7,9-decatrien-3-ones 1,3 and 6-methoxycarbonyl-2,8, 10-undecatrien-4-one 6 underwent smooth intramolecular Diels-Alder reactions selectively providing cis-cycloadducts when diethyl ether-boron trifluoride complex is employed as promoter. On the other hand, Lewis acids such as titanium(IV) bromide or tin(IV) chloride cause preferential formation of trans-octalones (methyl 1,2,3,4,4a,5,6,8a-octahydro-4-oxonaphthalene-2-carboxylates). Seven-membered ring chelates involving a keto group and an ester function as ligands for the Lewis acids with two free coordination sites are suggested as crucial intermediates.Keywords
This publication has 0 references indexed in Scilit: