Ammonia → Biotin

Participants

Reaction Steps

The PNA moiety was prepared by solid phase synthesis as described in Example 1 (1 μmol synthesis). A hydroxyethyleneglycine-based building block having guanine as the nucleobase (Formula VA; wherein TR is Dmt, U is oxygen, u′ is 2, PG is anisoyl and B is guanine) was coupled on in the last cycle. After eliminating the terminal Dmt group with 3% TCA, the free hydroxyl 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. 50-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, 63 OD of crude product was obtained. The crude product was purified by electrophoresis through a 15% PAA gel. 11.2 OD was obtained. The product was analyzed by negative ion mass spectrometry, which confirmed the calculated mass (calc. 3806.8; found 3807.2).

Provenance & Evidence