Study On The Synthesis Of P, N-heterocycles

The development of new synthetic methodologies for versatile heterocyles has attracted the attention of organic chemists. However, very few P, N-heterocycles have been described in the literature. Keeping in view the disadvantages associated with some of the reported procedures such as lengthy route, inconvenient procedure and low yields, there remains a need to develop a more efficient method. At first, the recent development on the synthetic methods of P, N-heterocyclics at home and abroad was reviewed. On the basis, the strategy of preparing P, N-heterocycles starting from hypophosphites through multicomponent reaction was established.Firstly, a series of fluorene or phenanthrene derivatives were synthesized via three component condensation involving arylaldehyde, malononitrile and 2-(1, 2-dihydro-inden-3-ylidene) malononitrile or 2-(2,3-Dihydronaphthalen-4(1H)-ylidene)- malononitrile which made me familiar with the characteristics and work-up of MCR. Then a series of Pyrano [2,3-d] pyrimidine derivatives were prepared in water via the condensation of arylidene malononitrile with 1,3-dimethyl barbital catalyzed by triethylbenzylammonium chloride. Further exploration on the synthesis of P, N-heterocycles were conducted. Although β- or γ-amino H-phosphinates were not attainable through reduction or Hoffmann degradation of the addition product of hypophosphites to acrylamide, Ciba-Geigy was found to be an efficient Michael donor to many activated vinyl promoted by Et ONa in spite of steric hindrance.The synthesis of substituted 3-ethoxy-1,3-azaphosphorinane-3-oxides via twostep was attempted. Ethyl phosphinte added to α, β- unsaturated ketones and gave ethyl(2-methyl-4-oxopentan-2-yl) phosphinate, which reacted with aldehyde and amine and produced 6-membered P, N-heterocycles. Taken with previously reported P, N-heterocycles synthesis, this methodology proved materials available, ecofriendly, mild and efficient. When the substrate was substituted for alkyne, hydrophosphinylation would take place and alkenyl phosphinates was given which condensated with aldehyde and amine and produced 5-membered P, N-heterocycles only via two steps. Taken with other reported literature,this methodology is highly atom-economic because only a mole of water was released after reaction.At last, triphenylphosphite reacted with aldehydes and urea promoted by equivalent TMSCl to give 1,4,2-diazaphspholidin-5-one-2-oxides, which expands the scope of 1,4,2-diazaphspholidin-5-one-2-oxides that can be obtained. Thus access to a wide variety of functionalized 1,4,2-diazaphspholidin-5-one-2-oxides should significantly enhance the synthetic usefulness of these compounds.The advantages of these reported reactions are simple operation, mild reaction conditions, short reaction time, high yields, and atomic economy. Possible reaction mechanisms were proposed in the dissertation, by which some unusual experiment results were explicited well.In this dissertation, 109 compounds have been synthesized and most of them were reported for the first time. All the structures of the products were confirmed on the basis of IR, NMR spectra, and high resolution mass spectrometry(HRMS), and some compounds were additionally confirmed by X-ray diffraction analysis.