Synthesis and transannular Diels-Alder reaction of a 13-membered macrocyclic triene. A synthetic approach towards the tricyclic part A.B.C.[6.6.5] of the veratrum alkaloids

Article abstract of DOI:10.1055/s-1992-34151

The syntheses of the acyclic triene cis-trans-trans (3Z,9Z,11E)-13-chloro-3-methoxy-1,1,7,7-tetrakis(methoxycarbonyl)-4- methyltrideca-3,9,11-triene (25), and the corresponding trans-cis-trans (3Z,9E,11E) isomer 37, and trans-trans-trans (3Z,9E,11E) isomer, 46, are described. Compounds 25 and 37 furnished in good yield 13-membered macrocyclic compounds (3Z,9Z,11E)- and (3Z,9E,11Z)-3-methoxy-1,1,7,7-tetrakis(methoxycarbonyl)-4- methylcyclotride-ca-3,9,11-triene (26) and (38) which led to tricyclic compound (cis-anti-cis)-2-methoxy-4,4,11,11-tetrakis(methoxycarbonyl)-1- methyl-tricyclo[7.4.0.0^2,6]tridec-7-ene (27) by transannular Diels-Alder reaction. Macrocyclization of trans-trans-trans chloride 46 was not successful.