Thiophene interconversions in Tagetes patula hairy-root cultures
1995
Arroo, R.R.J. | Jacobs, J.J.M.R. | Koning, E.A.H. de | Waard, M. de | Westerlo, E. van de | Galen, P.M. van | Swolfs, A.E.M. | Klunder, A.J.H. | Croes, A.F. | Wullems, G.J.
On the basis of feeding experiments with 35S-labelled intermediates, we present a modified biosynthetic pathway of the bithienyls in Tagetes. The monothiophene 2-(but-3-en-1-ynyl)-5{penta-1,3-diynyl)-thiophene, which is present in small amounts in Tagetes hairy roots, is the precursor of all bithienyls that have been described for this species but not of alpha-terthienyl. The current hypothesis that 5-(3-buten-1-ynyl)-2,2'-bithienyl originates from 5'-methyl5-(3-buten-1-ynyl)-2,2'-bithienyl after oxidative decarboxylation proved untrue. The latter compound is only converted into (5'-but-3-en-1-ynyl-[2,2']bithiophenyl-5-yl)-methyl acetate, probably via (5'-but-3-en-1-ynyl-[2,2']bithiophenyl5-yl)-methanol. Substitution of the butenynyl side chain of 5-(3-buten-l-ynyl)-2-2'-bithienyl results in the formation of 5-(3,4-dihydroxy-1-butynyl)-2,2'-bithienyl and 5-(4-hydroxy-1-butynyl)-2,2'-bithienyl, which are subsequently converted into respectively 5-(3,4-diacetoxy-1-butynyl)-2,2'-bithienyl and 5-(4-acetoxy-1-butynyl)-2,2'-bithienyl. The end products of this biosynthetic pathway are all bithienyl-acetate esters.
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