Adenine → Biotin

Participants

Reaction Steps

The PNA moiety was prepared by solid phase synthesis as described in Example 1 (2 μmol synthesis). In the last cycle, a normal PNA building block, having adenine as the nucleobase, was coupled on (Formula VA; wherein TR is Mmt, U is NH, u′ is 2, PG is anisoyl, and B is adenine). After eliminating the terminal Mmt group with 3% TCA, the free amino function was reacted with biotin-phosphoramidite 5 (FIG. 4b) using tetrazole as catalyst. This reaction employs an excess of the phosphorylating reagent (approx. 10-fold) as a 0.12 M solution in acetonitrile and the tetrazole (approx. 5-fold; 0.5 M in acetonitrile). After the condensation had taken place, oxidation was effected using an iodine solution (0.05 M in tetrahydrofuran/water, pyridine (7:2:1; v:v:v)). After cleaving with ammonia, 288 OD of crude product was obtained. The crude product was purified by electrophoresis through a 15% PAA gel. 17.5 OD was obtained. The product was analyzed by negative ion mass spectrometry, which confirmed the calculated mass (calc. 3789.6; found 3789.8).

Provenance & Evidence