冠醚合成.pdf

Tetrahedron Letters,Vol.23,No.l6,pp 1639-1642,1982 0040-4039/82/161639-04$03.00/O Printed in Great Britain 01982 Pergamon Press Ltd. SYNTHESES AND STRUCTURE OF STILBENE CROWNS. JulianTirado-Rives, Richard David Gandour*, and Frank Rolf Fronczek Department of Chemistry Louisiana State University Baton Rouge, LA 70803 Summar: Syntheses of r- and ~-[a,el-dibenzo-7,10,13-trioxacyclotrideca-l,3,5-triene, 1 (n=l7 and E- and Z-[a,e]-dibenzo-7,10,13,16-tetraoxacyclohexadeca-l,3,Etriene, ,J rn=2) are described and the X-ray structure of E-J (n=l) is reported. As part of a program to develop new chemical models for enzymatic catalysis, stilbene molecules in which the aromatic rings are restricted from rotating are desired. This re- striction should be readily accomplished by linking the 2,2 positions with an appropriate bridging moiety. Recent advances in synthetic methods for polyether podands2 and for cyclo- alkenes3 have suggested a straightforward approach to the desired molecules. This letter reports the facile two-step syntheses of a mixture of double bond isomers of stilbene crown ethers 4 (n=1,2) viz., E- and Z-[a,e]-dibenzo-7,10,13-trioxacyclotrideca-1,3,5-triene and E- and Z-[a.e]-dibenzo-7,10,13,16-tetraoxacyclohexadeca-1,3,5-triene. - CHO + OH Ti Cl4 *A0 “x