Table 1.

Temperature and solvent effects from the addition of DIBAL to 20a.^a

Solvent	Temp. (°C)	20a (%)	21 (%)	22 (%)
pentane	rt	26	19	55
cyclohexane	60	2	14	79
cyclohexane	81	0	15	85
toluene	111	10	7	83
xylenes	140	13	4	83

^aOne equivalent of DIBAL (1.0 M in cyclohexane) added to preheated solution of 20a (ca. 0.25 mmol, in 4 mL), stirred rapidly for 1 h, quenched with 20% aq w/v NaOH, extracted in EtOAc, washed with H₂O and brine, dried (MgSO₄) and evaporated. Yields of 21 and 22 estimated from ¹H NMR analysis of the crude mixture.