Fluorescein II CEP
Notes: For the installation of fluorescein at the 5'-terminus of an oligonucleotide while allowing multiple additions or assaying the coupling step.
Description: For the installation of fluorescein internally or at the 5'-terminus of an oligonucleotide, the phosphoramidite "6-FAM" (5'-Fluorescein CEP, BA 0054), which does not bear a DMT group, is a popular choice. However, the lack of a trityl group precludes multiple additions or assaying the coupling step. We therefore offer Fluorescein II CEP ("6-FAM II", BA 0253), which features the same tether length as 6-FAM, but includes a DMT group.1 Use normally, but with a 15 minute coupling. For the highest yields, prepare the oligo DMT-on and remove the trityl group after cleavage and deprotection. The DMT may also be used to facilitate cartridge purification with on-column detritylation, e.g. with Fluoro-Pak columns.
We also offer Fluorescein III CEP ("6-FAM III", BA
0334) with a DMT on a 1,3-diol framework. Download Product Information for BA 0253 here.
1. 5'-Fluorescein II CEP incorporates 6-carboxyfluorescein. The 5-carboxyfluorescein isomer of this product (CA Reg. No. 144676-14-2) is also known. See: Theisen, P.; McCollum, C.; Upadhya, K.; Jacobson, K.; Vu, H.; Andrus, A. Tetrahedron Lett. 1992, 33, 5033-5036.