title: Stereoselective addition of dimethyl thiophosphite to imines.
abstract: Dimethyl thiophosphite (DMTP) was synthesized from dimethyl phosphite, and the diastereoselective addition of DMTP to benzaldimines bearing chiral auxiliary groups was examined. Yields of the product alpha-aminophosphonothionates ranged from 17% to 75% after chromatography. The addition of DMTP to the benzaldimine derived from (S)-phenylglycinol afforded the highest diastereoselectivity (83:17), whereas addition of DMTP to the benzaldimine derived from threonine methyl ester and alanine methyl ester were far less diastereoselective, affording 38:62 and 61:39 ratios, respectively. Addition of DMTP to the benzaldimine derived from (R)-alpha-methylbenzylamine (78:22) and (S)-serine methyl ester (73:27) were intermediate in selectivity. DMTP addition to the imines formed between serine methyl ester and acetaldehyde and isobutyraldehyde gave 55:45 and 70:30 ratios, respectively, with the diastereoselectivity corresponding roughly to the size of the alpha-alkyl group. The stereochemistry of the newly formed alpha-stereocenters resulting from the addition of DMTP to (S)- and (R)-phenylglycinol benzaldimines was confirmed by conversion of the product alpha-aminophosphonothionates to the known enantiomers of phosphonophenylglycine.
authors.affiliation: Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, Montana 59812, USA.
authors.forename: Pakamas
authors.initials: P
authors.lastname: Tongcharoensirikul
authors.forename: Alirica I
authors.initials: AI
authors.lastname: Suarez
authors.forename: Troy
authors.initials: T
authors.lastname: Voelker
authors.forename: Charles M
authors.initials: CM
authors.lastname: Thompson
mesh_terms: D002384:Catalysis; D002845:Chromatography; D020650:Combinatorial Chemistry Techniques; D007097:Imines / Q000737:chemistry*; D007202:Indicators and Reagents; D015394:Molecular Structure; D009946:Organothiophosphorus Compounds / Q000032:analysis / Q000138:chemical synthesis*; D013237:Stereoisomerism; D013912:Threonine / Q000737:chemistry
chemical_list: D007097:Imines; D007202:Indicators and Reagents; D009946:Organothiophosphorus Compounds; C486057:dimethyl thiophosphite; D013912:Threonine