Meso-dihydrobenzoin

A series of meso-dihydrobenzoins was also subjected to oxidative desymmetrization. Three equivalents of the chiral ketone 88 again provided the chiral dioxirane as the active species [138, 139]. As shown in Table 10.14, enantiomeric excesses up to 60% were achieved. In addition to the meso diols themselves, acetonides also proved suitable substrates in two instances (Table 10.14). 

Adam et al. subjected a series of meso-dihydrobenzoins to oxidative desymmetrization, using three equivalents of the chiral Shi ketone 54 as catalyst. In the presence of peroxomonosulfate (Oxone, Curox etc.), the latter generates a chiral dkmrane as... 

Under mechanochemical conditions, bifunctional benzil 71 is specifically reduced by NaBU, when used in a 4 1 stoichiometric ratio to quantitatively give racemic benzoin 72 (Scheme 6.26). Such result has never been described in solution reactions of these reagents. Furthermore, both carbonyl groups of 71 were quantitatively reduced to dihydrobenzoin (17/18), if a 2 1 ratio of 71 and NaBU, was applied under the otherwise identical conditions of Table 6.17. This stoichiometric synthesis provides meso-13 and rac-74 in 80% and 20% yields, respectively. This stereoselectivity compares with the reported 100 0 ratio in methanol (2h at 25°C) and the 85 15 ratio of 73/74 in ethanol (overnight). 

---