The Synthesis Of (±)-Abscisic Acid And Its 2, 3-methylene Analogue

Abscisic acid is one of the natural plant hormone extensively distributed in higher plants and regulates many processes in plants such as the acceleration of abscission, induction of dormancy, inhibition of rooting, and stimulation of stomatal closure. In this thesis, we describe a facile and economical synthesis of (?-abscisic acid(l) from keto-isophorone and 3-butyn-2-ol through ketalization, oxidization, Witting-Horner reaction, reduction with chromium( II) sulfate and other steps in 13% total yields. Compared to the previous routes, the starting materials are more commercially available and cheaper and the synthetic process is more easily controlled in our method, but the yield of this route is still to be improved.As to isostere principle, cyclopropyl and methyl vinyl are a couple of isostere. Cis-C=C configuration on 2 position is easily isomerized to trans-form in environment according to literatures, but cycloproyl do it difficut relatively. So, replacement of 2,3- allyl unit by cyclopropyl group might give a practical method to get over the problem. For the interest of this opinion, we designed and synthesized compound (88) successfully through reactions such as cyclopropanation, nucleophilic addictions and selective reduction of triple bond etc.The structures of the target compounds and 15 intermediates have been confirmed by 1H NMR, 13C NMR, GC/MS and IR.