We hypothesized that compound 1 is half reduced by DIBAL-H forming the appropriate aluminoxy acetal, which is expected to be stable enough at temperatures as low as −78 °C. This is partly corrob- orated by the decomposition of the aluminoxy acetal to the over reduced alcohol when 1.4 equiv of DIBAL-H were used (Table 1, entries 1, 3 and 5) [24]. The presence of an alumi- noxy acetal is also supported when THF is used, although the yields are low, probably due to the destabilization of the alumi- noxy acetal (Table 1, entry 4) [25].