Chiral Diamines for a New Protocol To Determine the Enantiomeric Composition of Alcohols, Thiols, and Amines by 31P, 1H, 13C, and 19F NMR

Abstract

A new experimental protocol is described which greatly improves our recently reported method for the determination of the enantiomeric composition of alcohols, phenols, thiols, and amines. Thus, successive addition into the NMR tube of (1) a chiral fluorinated diamine (or any other chiral Cg symmetrical diamine), (2) CDCI3, (3) a tertiary amine, (4) PCI3, and 5) the chiral alcohol, phenol, thiol, or amine allows a 31P NMR spectrum of the diastereomeric derivatives to be recorded in 5 min. The method is accurate and very general, and no kinetic discrimination is observed. Sulfuration or selenation of the trivalent phosphorus derivatives, carried out in the NMR tube, allows for a second 31P NMR determination, in addition to the , 13C, and 19F NMR spectra which may also be recorded.

An efficient chiral phosphorus derivatizing agent for the determination of the enantiomeric excess of chiral alcohols and amines by 31P NMR spectroscopy

“…Moreover, we also compared the outcomes obtained by the use of CDA 1 with the results determined by polarimetry (entries [12][13][14]. We found that they agreed well with each other.…”

“…Moreover, the value of δ (5.10-8.38 ppm) is larger than the ones obtained from the other chiral phosphorus derivatizing agents reported previously. For example when rac-␣-methylphenylmethanol was used as the substrate, the δ (6.88 ppm) was much larger than the results determined by use of other chiral phosphorus derivatizing agents [11][12][13][14], which ranged from 0.10 ppm to 1.40 ppm.…”

A New Efficient Synthesis of (R,R)-2,2′-Bipyrrolidine: An Interesting Chiral 1,2-Diamine withC2 Symmetry

“…[ZnCl(C 8 H 16 N 2 ) 2 ] Cl À [ZnCl 2 (C 8 H 16 N 2 )] 2 (12): M r 969.9, m 2.11 mm À1 ; T min , T max 0.6732, 0.7366, d x 1.53g cm À3 , tetragonal, P4 1 2 1 2, Z 4, a 13.8279(6), c 22.0358(12) , U 4213.5(4) 3 . 52 049 measured reflections, 4110 unique reflections of which 3231 were observable j F o j> 4 s(F o )); R int for equivalent reflections 0.043.…”

“…This synthesis of (R,R)-2,2'-bipyrrolidine (9) could be carried out on a large scale (0.4 mol) in 61 % overall yield, starting from 6 and using only acid ± base wash purifications and a final distillation, with an ee value of > 99 % (the ee value was determined by 31 P NMR spectroscopy). [12] With (R,R)-2,2'-bipyrrolidine (9) in hand, we easily prepared the corresponding aminals 10 with several aldehydes, [13] by simple stirring of the diamine with the aldehyde, in diethyl ether at room temperature (Scheme 4). None of the reactions however, gave products suitable for X-ray crystallography.…”

Analytical Aspects of Amino, Quaternary Ammonium, Nitro, Nitroso and Related Functional Groups

“…Besides the 31 P NMR spectra of the diasteroisomers 186, also 1 H, 13 C and 19 F spectra may be taken. Addition of sulfur or selenium to the NMR tube will afford diasteroisomers 187, for which the corresponding spectra can also be taken 397 NMR assignment of configuration served for development of a method claimed to be of great reliability for establishing the absolute configuration of amines with an asymmetric center in the˛position, for which no reference compound is needed. The first step consists of derivatizing the amine with a chiral reagent, for example N-[(S)-2-methoxy-2-phenylacetoxy]succinimide (188), as shown in reaction 33 for the methyl ester of (R)-tyrosine.…”