Stereoselective addition of dimethyl thiophosphite to imines.
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.
Tongcharoensirikul
Pakamas
P
Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, Montana 59812, USA.
Suarez
Alirica I
AI
Voelker
Troy
T
Thompson
Charles M
CM
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
D007097:Imines; D007202:Indicators and Reagents; D009946:Organothiophosphorus Compounds; C486057:dimethyl thiophosphite; D013912:Threonine