Use of 13C as an Indirect Tag in 15N Specifically Labeled Nucleosides. Syntheses of [8-13C-1,7,NH2-15N3]Adenosine, -Guanosine, and Their Deoxy Analogues
摘要:
We have previously reported the use of a C-13 tag at the C2 of N-15-multilabeled purine nucleosides to distinguish the adjacent-labeled N-15 atoms from those in an untagged nucleoside. We now introduce the use of an indirect tag at the C8 of (15)N7-labeled purine nucleosides. This tag allows unambiguous differentiation between a pair of (15)N7-labeled purines in which only one is (13)C8 labeled. Although the very small C8-N7 coupling (< 1 Hz) precludes its direct detection in 1D N-15 spectra, 2D H-1-N-15 NMR experiments display the large C8-H8 coupling (>200 Hz) because H8 is coupled to both N7 and C8. The (13)C8 atom is introduced by means of a ring closure of the exocyclic amino groups of a pyrimidinone using [C-13] sodium ethyl xanthate. Here, we present methods for the syntheses of [8-C-13-1,7,NH2- N-15(3)]adenosine, -guanosine, and their deoxy analogues.
Use of 13C as an Indirect Tag in 15N Specifically Labeled Nucleosides. Syntheses of [8-13C-1,7,NH2-15N3]Adenosine, -Guanosine, and Their Deoxy Analogues
摘要:
We have previously reported the use of a C-13 tag at the C2 of N-15-multilabeled purine nucleosides to distinguish the adjacent-labeled N-15 atoms from those in an untagged nucleoside. We now introduce the use of an indirect tag at the C8 of (15)N7-labeled purine nucleosides. This tag allows unambiguous differentiation between a pair of (15)N7-labeled purines in which only one is (13)C8 labeled. Although the very small C8-N7 coupling (< 1 Hz) precludes its direct detection in 1D N-15 spectra, 2D H-1-N-15 NMR experiments display the large C8-H8 coupling (>200 Hz) because H8 is coupled to both N7 and C8. The (13)C8 atom is introduced by means of a ring closure of the exocyclic amino groups of a pyrimidinone using [C-13] sodium ethyl xanthate. Here, we present methods for the syntheses of [8-C-13-1,7,NH2- N-15(3)]adenosine, -guanosine, and their deoxy analogues.