Thioacids and thioacid salts for determining the enantiomeric excess of chiral compounds containing an electrophilic carbon center

A method of analyzing a test compound having an electrophilic carbon center, wherein the test compound is a compound of formula IIa or IIb,

• wherein X, Y, and Z are independently any atom or group, L is a leaving atom or group, Q is a group having an electrophilic carbon atom, none of L, X, Y, and Z is identical to each other and none of X, Y, Z, and Q-L is identical to each other;
• the method comprising reacting the test compound with a compound of formula I or a salt thereof,
• wherein R1, R2, and R3 are each independently (C1-C6)alkyl, (C3-C6)cycloalkyl, (C1-C6)alkoxy, aryl, aryloxy, aryl(C1-C3)alkyl, aryl(C1-C3)alkoxy, wherein any cycloalkyl, alkyl, or aryl group is optionally substituted with one or more halo, oxo, hydroxy, methoxy, ethoxy, acetoxy, acetamido, cyano, nitro, nitroso, methylmercapto, ethylmercapto, carboxyl, sulfonate, or sulfinate groups;
• and wherein any cycloalkyl or aryl group is additionally optionally substituted with one or more methyl or ethyl;
• wherein none of R1, R2, and R3 are identical to each other, and no two of R1, R2, and R3 are linked together to form a cycloalkyl or aryl ring;
• to form an adduct of formula IIIa or IIIb
• and analyzing the stereochemistry of the adduct to determine the stereochemistry of chiral center Ca or Cb in the adduct.