Chiral trimethylsilylated C₂-symmetrical diamines as phosphorous derivatizing agents for the determination of the enantiomeric excess of chiral alcohols by ¹H NMR

• Anne-Sophie Chauvin and
• Alexandre Alexakis

Beilstein J. Org. Chem. 2006, 2, No. 6, doi:10.1186/1860-5397-2-6

• agents (CDAs) developed contain an amine or a C2 symmetric diamine moiety, and have conveniently been applied to the determination of the enantiomeric excess (ee) of various chiral alcohols, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], amines,[6][13][14][21][22] thiols[3][10][12][13

• . Futhermore, these signals are very intense, due to the presence of nine equivalent protons for the three methyls of each trimethysilyl substituent. As observed in Table 2, the resolution of the signals is good enough, so that the determination of the enantiomeric excess by integration of each diastereoisomer

Synthesis of 2,6-trans- disubstituted 5,6-dihydropyrans from (Z)-1,5-syn-endiols

• Eric M. Flamme and
• William R. Roush

Beilstein J. Org. Chem. 2005, 1, No. 7, doi:10.1186/1860-5397-1-7

• enantiomeric excess of only 25% e.e. while the enantiomeric purity of the starting diol 2a was 91% e.e. This result suggests that the selectivity for displacement of the two hydroxyl groups of 2a is only ca. 2 : 1 under these conditions. Examination of molecular models indicates that in order for the activated