Table 6.

TEOC Protection of 54-α.

entry	solvent	Result
1a	CH2Cl2	54-α (>99%)
2b	CH2Cl2	54-α (>99%)
3c	CDCl3	biphasic mixture
		24 h; 87:85 = 52:48
4d	CDCl3	48 h; 87:85 = 16:84
		72 h; 87:85 = 0:100
5e	CDCl3	85 (92%)

^aA: i-Pr₂NEt (1055 equiv), −78 °C, 20 min; B: −78 °C, 1 h, (0.002 M); C: TMS-ethanol (18 equiv), −78 °C to rt, 4 h (0.0012 M).

^bA: i-Pr₂NEt (1055 equiv), −78 °C, 20 min; B: −78 °C to rt, 1 h, (0.002 M); C: TMS-ethanol (72 equiv), −78 °C to rt, 9 h (0.0012 M).

^cA: i-Pr₂NEt (28 equiv), −78 °C to rt, 30 min, (DMAP 0.6 M); B: −78 °C to rt, 1 h, (0.002 M); C: TMS-ethanol (72 equiv), −78 °C to rt, 9 h (0.0012 M).

^dA: −78 °C to rt, 1 h, (DMAP, 1.2 M); B; i-Pr₂NEt (28 eq), −78 °C to rt, 1 h, (0.043 M); C: TMS-ethanol (26 equiv), rt, (0.0041 M).

^eA: −78 °C to rt, 30 min, (DMAP 1.2 M); B: i-Pr₂NEt (28 equiv), −78 °C to rt, 1 h, (0.043 M); C: TMS-ethanol (26 equiv), rt, 12 h (0.043 M).