TABLE 1.

Mild removal of the 5’-O-DMTr group from the native and modified oligonucleotides (1–6) in Scheme 1^a

Oligo -entry	pH b	t1/2c (min)	Td (min)	Yielde (%)
1	5.0	6.5	45	99
2	5.0	10	60	99
3	4.5	9.4	60	98
4	4.5	8.6	60	98
5	5.0	11	60	98
6	4.5	7.8	60	97

^aAll experiments were carried out at 40 °C (± 1 °C);

^bpH measurement error (σ = ± 0.04);

^cthe half-life time for the DMTr removal: it was calculated from the following equation t_1/2 = ln (0.5) / ln (%DMTr-on/100) × t;

^dthe reaction time of detritylation reaction;

^ethe yields of the generated DMTr-off oligonucleotides (confirmed by MS analysis), which were measured via the peak area.