Compositions and methods for analyzing cysteine
The present invention relates to compositions and methods for determining the absolute configuration of D/L-cysteine and/or the enantiomeric composition of cysteine and/or the concentration of total cysteine in a sample. Uses of the composition and method are also described.
1. A compound of Formula I:
wherein:
each X is independently C or N;
each E is independently hydrogen or an electron withdrawing group selected from the group consisting of —CF 3 , —C(O)—R a , —SO 2 —R a , —CN, and —NO 2 , with the proviso that at least one E is an electron withdrawing group;
LG is a leaving group.
R 1 and R 2 , together with the carbon or nitrogen atoms to which they are attached, form a cycloalkyl, heterocycloalkyl, aryl, or heteroaryl;
R 3 is absent or selected from the group consisting of —R a , -cycloalkyl, -heterocycloalkyl, -aryl, and -heteroaryl; and
each R a is independently selected from the group consisting of —H, -alkyl, —O-alkyl, —N-alkyl, -alkenyl, —O-alkenyl, —N-alkenyl, -alkynyl, —O-alkynyl, —N—alkynyl, -aryl, —O-aryl, —N-aryl, -heteroaryl, —O-heteroaryl, —N-heteroaryl, -cycloalkyl, —O-cycloalkyl, —N-cycloalkyl, -heterocycloalkyl, —O—heterocycloalkyl, and —N-heterocycloalkyl;
wherein the compound of Formula I is not
2. The compound of claim 1 , wherein each X is C.
3. The compound of claim 1 , wherein each E is an electron withdrawing group.
4. The compound of claim 3 , wherein each E is —NO 2 .
5. The compound of claim 1 , wherein LG is a leaving group selected from the group consisting of halogen, —OR b , —OC(O)R b , —OS(O) 2 R b , —S(O) 2 —O—R b , —N 2 + , —N+(R b ) 3 , —S + (R b ) 2 , and —P + (R b ) 3 ; wherein each R b is independently selected from the group consisting of hydrogen, -alkyl, —O-alkyl, —N-alkyl, -alkenyl, —O-alkenyl, —N-alkenyl, -alkynyl, —O-alkynyl, —N-alkynyl, -perfluoroalkyl, -perfluoroalkenyl, -perfluoroalkynyl, -aryl, —O-aryl, —N-aryl, -heteroaryl, —O— heteroaryl, —N-heteroaryl, -cycloalkyl, —O-cycloalkyl, —N-cycloalkyl, -heterocycloalkyl, —O-heterocycloalkyl, and —N-heterocycloalkyl, except that R b is not p-tolyl when LG is —OS(O) 2 R b and R 1 and R 2 together form an aryl.
6. The compound of claim 5 , wherein the leaving group is
7. The compound of claim 6 , wherein the leaving group is
8. The compound of claim 1 , wherein R 1 and R 2 , together with the carbon atoms to which they are attached, form a cycloalkyl, aryl, or heteroaryl.
9. The compound of claim 8 , wherein R 1 and R 2 , together with the carbon atoms to which they are attached, form a naphthalene ring.
10. The compound of claim 1 , where R 3 are each hydrogen.
11. The compound of claim 1 , wherein the compound is