- Synthesis of gibberellin GA6 and its role in flowering of Lolium temulentum.
-
The induction of flowering by one long day (LD) in the grass Lolium temulentum is most closely mimicked by application of the gibberellins (GAs) GA(5) or GA(6), both of which occur naturally. These gibberellins promote floral development but have little effect on stem elongation. Endogenous GA(5) and GA(6) contents in the shoot apex double on the day after the LD and, for GA(5) (and we presume for GA(6) as well) reach a concentration known to be inductive for the excised shoot apex in vitro. They are, therefore, strong candidates as LD floral stimuli in this grass. The synthesis of GA(6) and an examination of its florigenic properties in L. temulentum are described.
- King, Rod W,Evans, Lloyd T,Mander, Lewis N,Moritz, Thomas,Pharis, Richard P,Twitchin, Bruce
-
-
- A NOVEL EXPEDITIOUS ENTRY INTO GIBBERELLINS. THE TOTAL SYNTHESIS OF (+/-)-GA5
-
A 16-step synthesis of (+/-)-GA5 (12), starting from m-methoxybenzoic acid, is described.Refunctionalization of the kinetic cycloadduct 4, obtained in 96 percent yield from the Diels-Alder reaction of furan 3 in water in the presence of β-cyclo
- Grootaert, Werner M.,Clercq, Pierre J. De
-
p. 1731 - 1734
(2007/10/02)
-
- Allylic Chlorination of Gibberellins A3 and A7 Methyl Esters and of Gibberellin A3: Preparation of Gibberellin A5
-
A high-yield conversion of gibberellin A3 to gibberellin A5 is described.With thionyl chloride, gibberellin A3 methyl ester gives mainly 1β-chlorogibberellin A5 methyl ester; the isomeric 3α-chloro-1-ene was the main product from the reaction with toluene-p-sulphonyl chloride and lithium chloride.Each product is reduced by tri-n-butylstannane and acetylated to give the same mixture of the 13-acetates of gibberellin A5 methyl ester and of the isomeric 1(10)-ene-19,2-lactone.Hydrolysis of gibberellin A5 methyl ester 13-acetate gives gibberellin A5 in 20percent overall yield from gibberellin A3. 2H1>Gibberellin A5 is obtained in the same way by using tri-n-butyl2H1>stannane in the reduction step.Analogous chlorination products of gibberellin A7 methyl ester and of gibberellin A3 are described.
- Bearder, John R.,Kirkwood, Paul S.,MacMillan, Jake
-
p. 672 - 678
(2007/10/02)
-
- Partial Synthesis of Gibberellin A9 and Gibberellin A9; Gibberellin A5 and Gibberellin A5; and Gibberellin A20 and Gibberellin A20
-
The 3α-alcohols, obtained by reduction of 3-didehydrogibberellin A3 methyl ester 13-acetate with lithium borohydride, borodeuteride, and borotritiide, have been converted into the 3β-chloro-derivatives and, hence, by reduction with tri-n-butylstannane followed by hydrolysis, into gibberellin A20, gibberellin A20, and gibberellin A20. Gibberellin A20 has been prepared from the product of the reduction of the 3-thiobenzoate of the 3α-alcohol with tri-n-butylstannane.The 3β-alcohols, minor products of these reductions, have been dehydrated and hydrolysed to give gibberellin A5 and gibberellin A5.The 3α-alcohol, from the lithium borohydride reduction of 3-didehydrogibberellin A7 has been transformed into the 3β-chloro-derivative and the 3-thiobenzoate which, with tri-n-butylstannane, or with tri-n-butylstannane, followed by hydrolysis, yielded gibberellin A9, gibberellin A9, or gibberellin A9.In an analogous way, the product of reduction of 3-didehydrogibberellin A4 with lithium borodeuteride was converted into gibberellin A9.The mass spectral fragmentation of the methyl esters and methyl ester trimethylsilyl ethers of gibberellins are also discussed.
- Beale, Michael H.,Gaskin, Paul,Kirkwood, Paul S.,MacMillan, Jake
-
p. 885 - 891
(2007/10/02)
-
