The addition of BF3·THF to an oxazaborolidine catalyst prepared in situ from chiral lactam alcohol 2 and borane enhanced the enantioselectivities (up to 90% ee) and yield (up to 91%) during the reduction of reactive trifluoromethyl ketones at room temperature.(S)-2,2,2-Trifluoro-1-biphenylethanolC14H11F3O[α]D25 = +22.7 (c 0.08, CHCl3), 90% eeSource of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-2,2,2-Trifluoro-1-(4-bromo-4′-biphenyl)ethanolC14H10BrF3O[α]D25 = +12.3 (c 0.08, CHCl3), 71% eeSource of chirality: Asymmetric synthesisAbsolute configulation: (S)

Two new growth inhibitory compounds, 6-O-decanoyl-d-altrose and 6-O-decanoyl-d-gulose, were synthesized from d-altrose (C-2 epimer of d-allose) and d-gulose (C-4 epimer of d-allose), respectively, via lipase-catalyzed transesterification using vinyl decanoate. Furthermore, the inhibitory activity of 6-O-decanoyl-d-altrose and 6-O-decanoyl-d-gulose on different plant growths were examined. These two new rare sugar derivatives exhibited the inhibitory activity on the growth of cress, Italian rye grass, and rice seedlings similar to 6-O-decanoyl-d-allose, but in the case of lettuce, they showed the weaker inhibitory activity than 6-O-decanoyl-d-allose. In addition, we found that the co-addition of gibberellins (GAs) with a test solution of 6-O-decanoyl-d-altrose or 6-O-decanoyl-d-gulose on rice seedlings brought the recovery of inhibition. These results suggest that the d-altrose and d-gulose esters as well as the d-allose ester inhibited the biosynthesis of GAs to exhibit the plant growth inhibitory activity.

The oxazaborolidine catalyst prepared in situ from the chiral lactam alcohol 3 and 4-iodophenoxyborane was found to catalyze the enantioselective reduction of α,β-enones at −40 °C with a high level of enantioselectivity of up to 90% ee.

The oxazaborolidine catalyst prepared in situ from the chiral lactam alcohol 2 and borane was found to catalyze the enantioselective reduction of highly reactive trifluoromethyl ketones at room temperature with high enantioselectivities of up to 86% ee.(S)-5-(Diphenylhydroxymethyl)pyrrolidin-2-oneC17H17NO2>99% ee[α]D25=+23.3 (c 0.21, CHCl3)Source of chirality: (S)-pyroglutamic acidAbsolute configuration: (S)(S)-5-[Bis(3,5-dimethylphenyl)hydroxymethyl]pyrrolidin-2-oneC21H25NO2>99% ee[α]D25=-35.3 (c 1.00, EtOH)Source of chirality: (S)-pyroglutamic acidAbsolute configuration: (S)(S)-2,2,2-Trifluoro-1-(4-methoxy-4′-biphenyl)ethanolC15H13F3O286% ee[α]D25=+22.7 (c 0.08, CHCl3)Source of chirality: asymmetric reductionAbsolute configuration: (S)

The diesterification of d-psicose (the C-3 epimer of d-fructose) with fatty acid vinyl esters of selected acyl chain lengths (C8, C10, and C12) was successfully carried out using Candida antarctica lipase (Novozym 435) at 45 °C for 24 h to give the 1,6-diacyl-d-psicofuranoses with a high regioselectivity in good yields (83–90%). These diesters of d-psicose have hydrophilic-lipophilic balance (HLB) values (6.5–8.2) similar to HLB values of monoglyceride compounds which constitute the largest single type of emulsifiers employed by the food industry. Ability of the d-psicose diesters to stabilize oil-in-water emulsions and the weight-averaged oil-droplet diameter in the emulsions was evaluated in this study. Emulsion stability of oil droplets stabilized by d-psicose dicaprylate (0.3%, w/v in oil phase) was comparable to d-fructose dicaprylate (0.2%, w/v). It was further confirmed that the d-psicose diesters exhibited an emulsification activity depending on the chain length of fatty acid; d-psicose dicaprate showed better emulsion stability than the other diesters.