Optically ActiveT-Butylphenylphosphinothioic Acid: Synthesis, Selected Structural Studies and Applications as a Chiral Solvating Agent

Abstract

Synthesis, structural studies and the use of the (−)-(S)-and (+)-(R) enantiomers of t-butylphenylphosphinothioic acid as a chiral solvating agent for the determination of enantiomeric purity is discussed. Systems that are the most extensively studied are emphasized.

Resolution of aryl-H-phosphinates applied in the synthesis of P-stereogenic compounds including a Brønsted acid NMR solvating agent

“…As the last step, we sought the applications of the compounds prepared in this study. ( S )-(1-Adamantyl)-phenylthiophosphonic acid [( S )- 3f ] seemed like a promising NMR chiral solvating agent (CSA), as it is a structural analogue of ( R )- t -butyl-phenylthiophosphinic acid, 31 and a few chiral phosphonothioic acids are known to behave as CSAs, as well. 18 d ,32 The optimization of the NMR parameters was performed with 1-(1-naphthyl)ethylamine ( 6 ) as the racemate, and using 1–1.5 equiv.…”

Towards Chemoenzymatic Syntheses of Both Enantiomers of Phosphoemeriamine

“…Their absolute configurations were not determined at this stage (vide infra), but the recovered substrate (+)- 12 was chemically acetylated to give (+)- 13 exhibiting almost the same value (though obviously of the opposite sign) of optical rotation as (−)- 13 , which could be taken as proof of the efficiency of the kinetic resolution ( Scheme 5 ). The enantiomeric excess of the recovered amine (+)- 12 was determined by 31 P NMR using optically pure (+)-( R )- t -butylphenylphosphinothioic acid as a chiral solvating agent [ 22 , 23 ]. In turn, the enantiomeric excess of the acetylation product, acetamide 13 , was determined on the basis of its optical rotation and via a chemical correlation shown in Scheme 5 .…”

A convenient route to symmetrically and unsymmetrically substituted 3,5-diaryl-2,4,6-trimethylpyridines via Suzuki–Miyaura cross-coupling reaction

“…In the case of compounds 46–49, 51–54 , and 68–71 , the steric hindrance caused by only one ortho -substituted aryl ring should generate the corresponding enentiomeric conformations, stable at least in the NMR time scale. Indeed, the presence of enantiomeric forms of 47 and 69 was confirmed by 1 H NMR recorded in the presence of (+)-butylphenylphosphinothioic acid [ 80 ] as a chiral solvating agent. Recently, we have employed a similar approach in the determination of the enantiomeric purity of (+)-crispine [ 81 ] and ( R )-(+)-harmicine after their stereoselective synthesis [ 82 ].…”