Study On The Formation Of Highly Unsaturated Bound Via Tripheylphosphine Mediated Deoxygenation Of Organic Compounds

Tremendous advancement has been made in organic phosphorus catalyzed or mediated reactions in organic synthetic reaction. It is shown that triphenylphosphine and its derivates play an important role in organic synthesis.They are primarily used as intermediates of organic phosphorus flame retardants and phosphorus ligands in biphasic water soluble catalysts. Not only regarded as ligands of transitional-metal, triphenylphosphine can also serve as promoter--deoxygenation agent in some case. Compared with transitional-metal catalyst, triphenylphosphine has the following feature:non-toxic;inexpensive and readily available; no heavy metals residue;easy to modify and load; separate conveniently for reuse and so on. All this make triphenylphosphine-promoted reaction meet with essential requirements of green chemistry.This dissertation take PPh3 promoted deoxygention as a key clue and aims to search for role that PPh3 played in divers reaction systems. It was proven that PPh3 can work as an intermediate to promote organic compounds containing oxgen atom deoxygenation for the formation of new carbon-carbon bond or unsaturated bond:1)Research on the synthesis of (E)-2-benzylidenesuccinates via tris(4-anisyl)phosphine-controlled reaction of arylaldehydes with maleic anhydride or dimethyl maleate. Arylmethylidenesuccinates, one of the important synthons, have been employed to synthesize 1,4-diphenylbutadiene derivatives,2,3-butanediol, (Z)-methyl a-(acetoxy)acrylates and (E)-β-aryl itaconate derivatives. However, a considerable body of synthetic methods for arylmethylidenesuccinates has not been entirely satisfactory. In our thesis, we have described the reaction of benzaldehydes with maleic anhydride or dimethyl maleate controlled by P(p-MeOC6H4)3. Through altering reaction substrates, additive, solvent and temperature we can get (E)-2-benzylidenesuccinates with high stereoselectivity in moderate to good yields under mild conditions.To the best of our knowledge, this protocol opened up a direct way for the synthesis of (E)-2-benzylidensuccinates, which are very important potential organic intermediates in organic synthesis. 2) Study on a facile synthesis of trisubstituted allenynes via phosphine-mediated deoxygenation of 2,4-pentadiyne-l-ol.Allenynes as a suite of highly unsaturated compounds can serve as precursors in the synthesis of highly complex or industrial importance and they are also important intermediates in organic synthesis.In addition, allenynes are present in many natural products and compounds with interesting biological activities Based on the study of our laboratory, a facile method for the synthesis of trisubstituented allenynes has been developed, involving the PPh3-mediated deoxygenation of propargyl alcohols.To the best of our knowledge, this is the first example of the preparation of an allenyne derivative directly from propargyl alcohol using an organocatalyst. This protocol casts light on future easy synthesis of natural product with the structure of conjugated allene and acetylenic bond.