Chiral diphosphite ligand and iridium composite catalyst and preparation thereof method and application to asymmetrical hydrogenization synthesis (S)-metolachlor

The invention relates to a kind of chiral diphosphite ligands, an iridium composite catalyst thereof, a preparation method and application thereof. The ligands are obtained through using chiral (R)-(S)-1-dimethylamino ethyiferroene as raw materials to react with diphenyl phosphonium chloride under the effect of butyl lithium and then to carry out displacement reaction with diaryl phosphine alkane. The chiral diphosphite ligands respectively act with homotropilidene compositions of iridous chloride, tetrabutyl ammonium iodide and glacial acetic acid, and imine asymmetrical hydrogenization catalysts can be obtained. When the iridium-diphosphine catalysts are used for catalyzing 2-methyl-6-ethyl-N-methylene aniline (EMA-imine) hydrogenization reaction, (S)-N-(1-anisyl-2-propyl)-2-methyl-6- ethylaniline ((S)-NNA) can be obtained, and the antimer excessive value (ee) can reach 86.5 percent. The (S)-NNA and chloracetyl chloride carry out acylation reaction to obtain (S)-metolachlor with the ee value of 86 percent. Thereby, the ligands provided by the invneiton can be used for synthesizing chiral herbicidal chemicals of (S)-metolachlor.